fix(decoration): strip 4 accent / status-hue leaks across hero surfaces

DESIGN.md 'Tunable-but-Scarce Rule' caps accent at <=10% of any
screen and reserves the accent + status hues for action / status,
never decoration. Four sites were spending those tokens on pure
chrome:

- Subscription.tsx purchased-traffic bar: zone.mainHex linear-gradient
  on a non-status progress bar; the per-purchase bar inherited the
  user's GLOBAL traffic-zone color (a fresh purchase could read
  'critical' just because the user's overall usage was). Replaced
  with solid accent-500 fill — same affordance, honest semantics.

- SubscriptionCardActive tariff badge: zone-colored linear-gradient
  background + zone-colored label. The tariff name has no traffic-zone
  semantics, so tinting it by the global traffic zone was a
  Status-Hue Lockout violation. Switched to glass innerBg/innerBorder.

- Balance hero card: bg-gradient-to-br from-accent-500/10 + glow prop
  on Card. Removed; flat surface, the giant numeric is the affordance.
  Eliminates the SaaS hero-metric template tell.

- Login background: two stacked fixed inset gradients (linear +
  accent radial halo) read as the airdrop / crypto aesthetic
  PRODUCT.md explicitly anti-references. Replaced with the plain
  body bg-dark-950.

src/components/dashboard/SubscriptionCardActive.tsx

@@ -282,18 +282,20 @@ export default function SubscriptionCardActive({
 
       {/* ─── Stats row: Tariff + Days Left ─── */}
       <div className="mb-5 flex gap-2.5">
-        {/* Tariff badge — clickable */}
+        {/* Tariff badge — clickable. Neutral chrome: the tariff name has
+            no traffic-zone semantics, so tinting it by the traffic zone
+            (DESIGN.md Status-Hue Lockout) was wrong. */}
         <Link
           to={`/subscriptions/${subscription.id}`}
-          className="flex-1 rounded-[14px] p-3.5 transition-all duration-500"
+          className="flex-1 rounded-[14px] p-3.5 transition-colors"
           style={{
-            background: `linear-gradient(135deg, rgba(${zone.mainVarRaw}, 0.07), rgba(${zone.mainVarRaw}, 0.02))`,
+            background: g.innerBg,
-            border: `1px solid rgba(${zone.mainVarRaw}, 0.09)`,
+            border: `1px solid ${g.innerBorder}`,
           }}
         >
           <div
-            className="mb-1.5 text-[10px] font-semibold uppercase tracking-wider opacity-70 transition-colors duration-500"
+            className="mb-1.5 text-[10px] font-semibold uppercase tracking-wider"
-            style={{ color: zone.mainVar }}
+            style={{ color: g.textFaint }}
           >
             {t('dashboard.tariff')}
           </div>

src/pages/Balance.tsx

@@ -210,9 +210,12 @@ export default function Balance() {
         <h1 className="text-2xl font-bold text-dark-50 sm:text-3xl">{t('balance.title')}</h1>
       </motion.div>
 
-      {/* Balance Card */}
+      {/* Balance Card — flat surface; the giant numeric carries the
+          weight. The previous accent gradient + glow leaked accent into
+          decoration (DESIGN.md Tunable-but-Scarce Rule) and read as the
+          SaaS hero-metric template. */}
       <motion.div variants={staggerItem}>
-        <Card className="bg-gradient-to-br from-accent-500/10 to-transparent" glow>
+        <Card>
           <div className="mb-2 text-sm text-dark-400">{t('balance.currentBalance')}</div>
           <div className="text-4xl font-bold text-dark-50 sm:text-5xl">
             {formatAmount(balanceData?.balance_rubles || 0)}

src/pages/Login.tsx

@@ -321,9 +321,10 @@ export default function Login() {
           safeBottom > 0 ? `${safeBottom + 16}px` : 'calc(1rem + env(safe-area-inset-bottom, 0px))',
       }}
     >
-      {/* Background gradient */}
+      {/* Flat background — the previous two layered gradients (linear
-      <div className="fixed inset-0 bg-gradient-to-br from-dark-950 via-dark-900 to-dark-950" />
+          + accent radial halo) read as the airdrop / crypto aesthetic
-      <div className="fixed inset-0 bg-[radial-gradient(ellipse_at_top,_var(--tw-gradient-stops))] from-accent-500/10 via-transparent to-transparent" />
+          PRODUCT.md explicitly anti-references. Body bg-dark-950 carries
+          the surface alone. */}
 
       {/* Language switcher */}
       <div

src/pages/Subscription.tsx

@@ -1046,10 +1046,9 @@ export default function Subscription() {
                           style={{ background: g.trackBg }}
                         >
                           <div
-                            className="absolute inset-0 origin-left rounded-full transition-transform duration-500"
+                            className="absolute inset-0 origin-left rounded-full bg-accent-500 transition-transform duration-500"
                             style={{
                               transform: `scaleX(${purchase.progress_percent / 100})`,
-                              background: `linear-gradient(90deg, ${zone.mainHex}, ${zone.mainHex}80)`,
                             }}
                           />
                         </div>