feat: add external squad selection to tariff admin form

- Add ExternalSquadInfo type and getAvailableExternalSquads API method
- Add external_squad_uuid field to TariffDetail, TariffCreateRequest, TariffUpdateRequest
- Add radio-button external squad picker in Servers tab of tariff create/edit
- Add translations for external squad UI in all 4 locales (en, ru, zh, fa)

src/pages/AdminTariffCreate.tsx

@@ -9,6 +9,7 @@ import {
   TariffUpdateRequest,
   PeriodPrice,
   ServerInfo,
+  ExternalSquadInfo,
 } from '../api/tariffs';
 import { AdminBackButton } from '../components/admin';
 import { createNumberInputHandler, toNumber } from '../utils/inputHelpers';
@@ -105,6 +106,7 @@ export default function AdminTariffCreate() {
   const [tierLevel, setTierLevel] = useState<number | ''>(1);
   const [periodPrices, setPeriodPrices] = useState<PeriodPrice[]>([]);
   const [selectedSquads, setSelectedSquads] = useState<string[]>([]);
+  const [selectedExternalSquad, setSelectedExternalSquad] = useState<string | null>(null);
   const [selectedPromoGroups, setSelectedPromoGroups] = useState<number[]>([]);
   const [dailyPriceKopeks, setDailyPriceKopeks] = useState<number | ''>(0);
 
@@ -138,6 +140,12 @@ export default function AdminTariffCreate() {
     queryFn: () => tariffsApi.getAvailableServers(),
   });
 
+  // Fetch external squads
+  const { data: externalSquads = [] } = useQuery({
+    queryKey: ['admin-tariffs-external-squads'],
+    queryFn: () => tariffsApi.getAvailableExternalSquads(),
+  });
+
   // Fetch promo groups
   const { data: promoGroups = [] } = useQuery({
     queryKey: ['admin-tariffs-promo-groups'],
@@ -165,6 +173,7 @@ export default function AdminTariffCreate() {
       setTierLevel(data.tier_level || 1);
       setPeriodPrices(data.period_prices?.length ? data.period_prices : []);
       setSelectedSquads(data.allowed_squads || []);
+      setSelectedExternalSquad(data.external_squad_uuid || null);
       setSelectedPromoGroups(
         data.promo_groups?.filter((pg) => pg.is_selected).map((pg) => pg.id) || [],
       );
@@ -211,6 +220,7 @@ export default function AdminTariffCreate() {
       tier_level: toNumber(tierLevel, 1),
       period_prices: isDaily ? [] : periodPrices.filter((p) => p.price_kopeks >= 0),
       allowed_squads: selectedSquads,
+      external_squad_uuid: selectedExternalSquad || null,
       promo_group_ids: selectedPromoGroups.length > 0 ? selectedPromoGroups : undefined,
       traffic_topup_enabled: trafficTopupEnabled,
       traffic_topup_packages: trafficTopupPackages,
@@ -660,6 +670,77 @@ export default function AdminTariffCreate() {
 
       {activeTab === 'servers' && (
         <div className="space-y-4">
+          {/* External Squad */}
+          {externalSquads.length > 0 && (
+            <div className="card space-y-4">
+              <h4 className="text-sm font-medium text-dark-200">
+                {t('admin.tariffs.externalSquadTitle')}
+              </h4>
+              <p className="text-sm text-dark-400">{t('admin.tariffs.externalSquadHint')}</p>
+              <div className="space-y-2">
+                <button
+                  type="button"
+                  onClick={() => setSelectedExternalSquad(null)}
+                  className={`flex w-full items-center gap-3 rounded-lg p-3 text-left transition-colors ${
+                    !selectedExternalSquad
+                      ? isDaily
+                        ? 'bg-warning-500/20 text-warning-300'
+                        : 'bg-accent-500/20 text-accent-300'
+                      : 'bg-dark-800 text-dark-300 hover:bg-dark-700'
+                  }`}
+                >
+                  <div
+                    className={`flex h-5 w-5 items-center justify-center rounded-full ${
+                      !selectedExternalSquad
+                        ? isDaily
+                          ? 'bg-warning-500 text-white'
+                          : 'bg-accent-500 text-white'
+                        : 'bg-dark-600'
+                    }`}
+                  >
+                    {!selectedExternalSquad && <CheckIcon />}
+                  </div>
+                  <span className="flex-1 text-sm font-medium">
+                    {t('admin.tariffs.noExternalSquad')}
+                  </span>
+                </button>
+                {externalSquads.map((squad: ExternalSquadInfo) => {
+                  const isSelected = selectedExternalSquad === squad.uuid;
+                  return (
+                    <button
+                      key={squad.uuid}
+                      type="button"
+                      onClick={() => setSelectedExternalSquad(squad.uuid)}
+                      className={`flex w-full items-center gap-3 rounded-lg p-3 text-left transition-colors ${
+                        isSelected
+                          ? isDaily
+                            ? 'bg-warning-500/20 text-warning-300'
+                            : 'bg-accent-500/20 text-accent-300'
+                          : 'bg-dark-800 text-dark-300 hover:bg-dark-700'
+                      }`}
+                    >
+                      <div
+                        className={`flex h-5 w-5 items-center justify-center rounded-full ${
+                          isSelected
+                            ? isDaily
+                              ? 'bg-warning-500 text-white'
+                              : 'bg-accent-500 text-white'
+                            : 'bg-dark-600'
+                        }`}
+                      >
+                        {isSelected && <CheckIcon />}
+                      </div>
+                      <span className="flex-1 text-sm font-medium">{squad.name}</span>
+                      <span className="text-xs text-dark-500">
+                        {squad.members_count} {t('admin.tariffs.externalSquadUsers')}
+                      </span>
+                    </button>
+                  );
+                })}
+              </div>
+            </div>
+          )}
+
           {/* Servers */}
           <div className="card space-y-4">
             <h4 className="text-sm font-medium text-dark-200">{t('admin.tariffs.serversTitle')}</h4>