refactor: extract purchase/renewal flow to separate page

Move ~1900 lines of purchase/renewal logic from Subscription.tsx into
a new SubscriptionPurchase.tsx page at /subscription/purchase.

- Create SubscriptionPurchase.tsx with tariffs grid, classic mode wizard,
  switch preview modal, and promo handling
- Create PurchaseCTAButton.tsx with animated gradient border, state-aware
  colors and context-aware text
- Create subscriptionHelpers.ts with shared utilities
- Add CopyIcon to shared icons module
- Register /subscription/purchase route with lazy loading
- Update SubscriptionCardExpired and PromoOffersSection navigators
- Add CTA translation keys to ru.json and en.json
- Remove all scrollToExtend references

src/components/icons/index.tsx

@@ -242,6 +242,22 @@ export const CheckIcon = ({ className }: IconProps) => (
   </svg>
 );
 
+export const CopyIcon = ({ className }: IconProps) => (
+  <svg
+    className={cn('h-4 w-4', className)}
+    fill="none"
+    viewBox="0 0 24 24"
+    stroke="currentColor"
+    strokeWidth={1.5}
+  >
+    <path
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      d="M15.666 3.888A2.25 2.25 0 0013.5 2.25h-3c-1.03 0-1.9.693-2.166 1.638m7.332 0c.055.194.084.4.084.612v0a.75.75 0 01-.75.75H9a.75.75 0 01-.75-.75v0c0-.212.03-.418.084-.612m7.332 0c.646.049 1.288.11 1.927.184 1.1.128 1.907 1.077 1.907 2.185V19.5a2.25 2.25 0 01-2.25 2.25H6.75A2.25 2.25 0 014.5 19.5V6.257c0-1.108.806-2.057 1.907-2.185a48.208 48.208 0 011.927-.184"
+    />
+  </svg>
+);
+
 export const XIcon = ({ className }: IconProps) => (
   <svg
     className={cn('h-4 w-4', className)}