feat(gift): transferable gift claim — buyer share link + recipient claim page

Pairs with the bot's unified claimable-gift model. A landing gift now lands on
the buyer's success page as PAID/claimable (deferred) instead of being delivered
to a phantom recipient, so the buyer gets a transferable link to forward and the
recipient claims it themselves — guaranteeing delivery regardless of channel or
whether they pre-exist.

- api/landings.ts: PurchaseStatus gains is_claimable/claim_url/bot_claim_link;
  add GiftClaimResult + getGiftClaim()/claimGift().
- PurchaseSuccess.tsx: GiftLinkShareState — buyer sees the claim link + Telegram
  link + copy-message when a gift is PAID/claimable; stop polling for that state
  (it stays PAID until claimed) instead of spinning forever.
- GiftClaim.tsx (new) + /buy/gift/:token route: public recipient claim page with
  a Telegram arm (GIFT_ deep link) and a web/email arm (binds + one-click login),
  polling while the payment settles, idempotent "already claimed" + 404 states.
- i18n: landing.giftClaim.* / landing.giftLink.* in ru/en/zh/fa.

src/App.tsx

@@ -65,6 +65,7 @@ const Connection = lazyWithRetry(() => import('./pages/Connection'));
 const ConnectionQR = lazyWithRetry(() => import('./pages/ConnectionQR'));
 const QuickPurchase = lazyWithRetry(() => import('./pages/QuickPurchase'));
 const PurchaseSuccess = lazyWithRetry(() => import('./pages/PurchaseSuccess'));
+const GiftClaim = lazyWithRetry(() => import('./pages/GiftClaim'));
 const RenewSubscription = lazyWithRetry(() => import('./pages/RenewSubscription'));
 const AutoLogin = lazyWithRetry(() => import('./pages/AutoLogin'));
 const TopUpMethodSelect = lazyWithRetry(() => import('./pages/TopUpMethodSelect'));
@@ -276,6 +277,14 @@ function App() {
             </LazyPage>
           }
         />
+        <Route
+          path="/buy/gift/:token"
+          element={
+            <LazyPage>
+              <GiftClaim />
+            </LazyPage>
+          }
+        />
         <Route
           path="/buy/:slug"
           element={