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
