redesign: admin subscription tab — two-level navigation for multi-tariff

Level 1 (subscription list):
- Cards with tariff name, status badge, traffic, date, devices
- Click to drill into subscription detail
- "Создать подписку" with filtered purchased tariffs

Level 2 (subscription detail):
- Back button to return to list
- All actions scoped to selected subscription
- No "Сменить тариф" in multi-subscription mode
- Panel info, devices, traffic stats per-subscription

Single subscription: keeps current behavior (direct detail view)

src/pages/AdminUserDetail.tsx

@@ -336,6 +336,7 @@ export default function AdminUserDetail() {
   const [subDays, setSubDays] = useState<number | ''>(30);
   const [selectedTariffId, setSelectedTariffId] = useState<number | null>(null);
   const [activeSubscriptionId, setActiveSubscriptionId] = useState<number | null>(null);
+  const [subscriptionDetailView, setSubscriptionDetailView] = useState(false);
 
   // Promo group
   const [promoGroups, setPromoGroups] = useState<PromoGroup[]>([]);
@@ -1379,40 +1380,133 @@ export default function AdminUserDetail() {
         {/* Subscription Tab */}
         {activeTab === 'subscription' && (
           <div className="space-y-4">
-            {/* Subscription selector (when multiple) */}
-            {userSubscriptions.length > 1 && (
-              <div className="rounded-xl bg-dark-800/50 p-4">
-                <div className="mb-2 text-xs font-medium text-dark-500">
-                  {t('admin.users.detail.subscription.selectSubscription', 'Выберите подписку')} (
-                  {userSubscriptions.length})
-                </div>
-                <div className="flex flex-wrap gap-2">
+            {/* Multi-subscription: Level 1 — subscription list */}
+            {userSubscriptions.length > 1 && !subscriptionDetailView && (
+              <>
+                <div className="space-y-3">
                   {userSubscriptions.map((sub) => (
                     <button
                       key={sub.id}
-                      onClick={() => setActiveSubscriptionId(sub.id)}
-                      className={`rounded-lg px-3 py-1.5 text-sm transition-all ${
-                        activeSubscriptionId === sub.id
-                          ? 'bg-accent-500 text-white'
-                          : 'bg-dark-700/50 text-dark-300 hover:bg-dark-700'
-                      }`}
+                      onClick={() => {
+                        setActiveSubscriptionId(sub.id);
+                        setSubscriptionDetailView(true);
+                      }}
+                      className="w-full rounded-xl border border-dark-700/50 bg-dark-800/50 p-4 text-left transition-all hover:border-dark-600"
                     >
-                      <span className="flex items-center gap-1.5">
-                        <span
-                          className={`inline-block h-2 w-2 rounded-full ${
-                            sub.is_active ? 'bg-emerald-400' : 'bg-red-400'
-                          }`}
-                        />
-                        {sub.tariff_name || `#${sub.id}`}
-                      </span>
+                      <div className="flex items-center justify-between">
+                        <div className="flex items-center gap-2">
+                          <span className="text-sm font-semibold text-dark-100">
+                            {sub.tariff_name || `#${sub.id}`}
+                          </span>
+                          <StatusBadge status={sub.status} />
+                        </div>
+                        <svg
+                          className="h-4 w-4 text-dark-500"
+                          fill="none"
+                          viewBox="0 0 24 24"
+                          stroke="currentColor"
+                          strokeWidth={2.5}
+                        >
+                          <path
+                            strokeLinecap="round"
+                            strokeLinejoin="round"
+                            d="M8.25 4.5l7.5 7.5-7.5 7.5"
+                          />
+                        </svg>
+                      </div>
+                      <div className="mt-2 flex items-center gap-4 text-xs text-dark-400">
+                        <span>
+                          {sub.traffic_used_gb.toFixed(1)} / {sub.traffic_limit_gb}{' '}
+                          {t('common.units.gb')}
+                        </span>
+                        <span>{formatDate(sub.end_date)}</span>
+                        <span>
+                          {sub.device_limit}{' '}
+                          {t('admin.users.detail.subscription.devices', 'устройств')}
+                        </span>
+                      </div>
                     </button>
                   ))}
                 </div>
-              </div>
+
+                {/* Create new subscription — at list level */}
+                {hasPermission('users:subscription') && (
+                  <div className="rounded-xl bg-dark-800/50 p-4">
+                    <div className="mb-3 text-sm font-medium text-dark-200">
+                      {t('admin.users.detail.subscription.createNew', 'Создать подписку')}
+                    </div>
+                    <div className="space-y-3">
+                      <select
+                        value={selectedTariffId || ''}
+                        onChange={(e) =>
+                          setSelectedTariffId(e.target.value ? parseInt(e.target.value) : null)
+                        }
+                        className="input"
+                      >
+                        <option value="">
+                          {t('admin.users.detail.subscription.selectTariff')}
+                        </option>
+                        {tariffs
+                          .filter((tariffItem) => {
+                            const purchasedIds = new Set(
+                              userSubscriptions
+                                .filter((s) => s.is_active || s.status === 'trial')
+                                .map((s) => s.tariff_id),
+                            );
+                            return !purchasedIds.has(tariffItem.id);
+                          })
+                          .map((tariffItem) => (
+                            <option key={tariffItem.id} value={tariffItem.id}>
+                              {tariffItem.name}
+                            </option>
+                          ))}
+                      </select>
+                      <input
+                        type="number"
+                        value={subDays}
+                        onChange={createNumberInputHandler(setSubDays, 1)}
+                        placeholder={t('admin.users.detail.subscription.days')}
+                        className="input"
+                        min={1}
+                        max={3650}
+                      />
+                      <button
+                        onClick={() => handleUpdateSubscription('create')}
+                        disabled={actionLoading}
+                        className="btn-primary w-full"
+                      >
+                        {actionLoading
+                          ? t('admin.users.detail.subscription.creating')
+                          : t('admin.users.detail.subscription.create')}
+                      </button>
+                    </div>
+                  </div>
+                )}
+              </>
             )}
 
-            {selectedSub ? (
+            {/* Level 2 — subscription detail (or single subscription) */}
+            {(subscriptionDetailView || userSubscriptions.length <= 1) && selectedSub ? (
               <>
+                {/* Back to list (multi-subscription) */}
+                {subscriptionDetailView && userSubscriptions.length > 1 && (
+                  <button
+                    onClick={() => setSubscriptionDetailView(false)}
+                    className="flex items-center gap-1.5 text-sm text-dark-400 transition-colors hover:text-dark-200"
+                  >
+                    <svg
+                      className="h-4 w-4"
+                      fill="none"
+                      viewBox="0 0 24 24"
+                      stroke="currentColor"
+                      strokeWidth={2}
+                    >
+                      <path strokeLinecap="round" strokeLinejoin="round" d="M15 19l-7-7 7-7" />
+                    </svg>
+                    {t('admin.users.detail.subscription.backToList', 'Все подписки')}
+                  </button>
+                )}
+
                 {/* Current subscription */}
                 <div className="rounded-xl bg-dark-800/50 p-4">
                   <div className="mb-3 flex items-center justify-between">
@@ -1602,9 +1696,11 @@ export default function AdminUserDetail() {
                         <option value="shorten">
                           {t('admin.users.detail.subscription.shorten')}
                         </option>
-                        <option value="change_tariff">
-                          {t('admin.users.detail.subscription.changeTariff')}
-                        </option>
+                        {userSubscriptions.length <= 1 && (
+                          <option value="change_tariff">
+                            {t('admin.users.detail.subscription.changeTariff')}
+                          </option>
+                        )}
                         <option value="cancel">
                           {t('admin.users.detail.subscription.cancel')}
                         </option>
@@ -1661,66 +1757,67 @@ export default function AdminUserDetail() {
               </>
             ) : null}
 
-            {/* Create new subscription (shown when no subs, or always in multi-tariff) */}
-            {hasPermission('users:subscription') && (
-              <div className="rounded-xl bg-dark-800/50 p-4">
-                {userSubscriptions.length === 0 && (
-                  <div className="mb-4 text-center text-dark-400">
-                    {t('admin.users.detail.subscription.noActive')}
+            {/* Create new subscription (shown when no subs, or single-tariff mode) */}
+            {hasPermission('users:subscription') &&
+              !(subscriptionDetailView && userSubscriptions.length > 1) && (
+                <div className="rounded-xl bg-dark-800/50 p-4">
+                  {userSubscriptions.length === 0 && (
+                    <div className="mb-4 text-center text-dark-400">
+                      {t('admin.users.detail.subscription.noActive')}
+                    </div>
+                  )}
+                  <div className="mb-3 text-sm font-medium text-dark-200">
+                    {t('admin.users.detail.subscription.createNew', 'Создать подписку')}
+                  </div>
+                  <div className="space-y-3">
+                    <select
+                      value={selectedTariffId || ''}
+                      onChange={(e) =>
+                        setSelectedTariffId(e.target.value ? parseInt(e.target.value) : null)
+                      }
+                      className="input"
+                    >
+                      <option value="">{t('admin.users.detail.subscription.selectTariff')}</option>
+                      {tariffs
+                        .filter((tariffItem) => {
+                          // In multi-tariff: hide tariffs user already has
+                          if (userSubscriptions.length > 0) {
+                            const purchasedIds = new Set(
+                              userSubscriptions
+                                .filter((s) => s.is_active || s.status === 'trial')
+                                .map((s) => s.tariff_id),
+                            );
+                            return !purchasedIds.has(tariffItem.id);
+                          }
+                          return true;
+                        })
+                        .map((tariffItem) => (
+                          <option key={tariffItem.id} value={tariffItem.id}>
+                            {tariffItem.name}
+                          </option>
+                        ))}
+                    </select>
+                    <input
+                      type="number"
+                      value={subDays}
+                      onChange={createNumberInputHandler(setSubDays, 1)}
+                      placeholder={t('admin.users.detail.subscription.days')}
+                      className="input"
+                      min={1}
+                      max={3650}
+                    />
+                    <button
+                      onClick={() => handleUpdateSubscription('create')}
+                      disabled={actionLoading}
+                      className="btn-primary w-full"
+                    >
+                      {actionLoading
+                        ? t('admin.users.detail.subscription.creating')
+                        : t('admin.users.detail.subscription.create')}
+                    </button>
                   </div>
-                )}
-                <div className="mb-3 text-sm font-medium text-dark-200">
-                  {t('admin.users.detail.subscription.createNew', 'Создать подписку')}
                 </div>
-                <div className="space-y-3">
-                  <select
-                    value={selectedTariffId || ''}
-                    onChange={(e) =>
-                      setSelectedTariffId(e.target.value ? parseInt(e.target.value) : null)
-                    }
-                    className="input"
-                  >
-                    <option value="">{t('admin.users.detail.subscription.selectTariff')}</option>
-                    {tariffs
-                      .filter((tariffItem) => {
-                        // In multi-tariff: hide tariffs user already has
-                        if (userSubscriptions.length > 0) {
-                          const purchasedIds = new Set(
-                            userSubscriptions
-                              .filter((s) => s.is_active || s.status === 'trial')
-                              .map((s) => s.tariff_id),
-                          );
-                          return !purchasedIds.has(tariffItem.id);
-                        }
-                        return true;
-                      })
-                      .map((tariffItem) => (
-                        <option key={tariffItem.id} value={tariffItem.id}>
-                          {tariffItem.name}
-                        </option>
-                      ))}
-                  </select>
-                  <input
-                    type="number"
-                    value={subDays}
-                    onChange={createNumberInputHandler(setSubDays, 1)}
-                    placeholder={t('admin.users.detail.subscription.days')}
-                    className="input"
-                    min={1}
-                    max={3650}
-                  />
-                  <button
-                    onClick={() => handleUpdateSubscription('create')}
-                    disabled={actionLoading}
-                    className="btn-primary w-full"
-                  >
-                    {actionLoading
-                      ? t('admin.users.detail.subscription.creating')
-                      : t('admin.users.detail.subscription.create')}
-                  </button>
-                </div>
-              </div>
-            )}
+              )}
 
             {/* Panel Info */}
             {panelInfoLoading ? (