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(${zone.mainVarRaw}, 0.02))`,
-            border: `1px solid rgba(${zone.mainVarRaw}, 0.09)`,
+            background: g.innerBg,
+            border: `1px solid ${g.innerBorder}`,
           }}
         >
           <div
-            className="mb-1.5 text-[10px] font-semibold uppercase tracking-wider opacity-70 transition-colors duration-500"
-            style={{ color: zone.mainVar }}
+            className="mb-1.5 text-[10px] font-semibold uppercase tracking-wider"
+            style={{ color: g.textFaint }}
           >
             {t('dashboard.tariff')}
           </div>