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/api/landings.ts

@@ -137,6 +137,21 @@ export interface PurchaseStatus {
   auto_login_token: string | null;
   recipient_in_bot: boolean | null;
   bot_link: string | null;
+  // Transferable gift claim link — the buyer forwards this; whoever activates it
+  // gets the gift. Derived from token + status (purchase.user is null until claim).
+  is_claimable: boolean;
+  claim_url: string | null;
+  bot_claim_link: string | null;
+}
+
+/** Result returned to the recipient after a successful web (email) gift claim. */
+export interface GiftClaimResult {
+  status: string;
+  tariff_name: string | null;
+  period_days: number | null;
+  subscription_url: string | null;
+  subscription_crypto_link: string | null;
+  auto_login_token: string | null;
 }
 
 /** Locale dict for multi-language text fields (admin API) */
@@ -282,6 +297,18 @@ export const landingApi = {
     const response = await apiClient.post(`/cabinet/landing/activate/${token}`);
     return response.data;
   },
+
+  // Public gift claim page data (no auth — the token is the bearer secret).
+  getGiftClaim: async (token: string): Promise<PurchaseStatus> => {
+    const response = await apiClient.get(`/cabinet/landing/gift/${token}`);
+    return response.data;
+  },
+
+  // Web (email) arm of the gift claim — binds the gift to the given email account.
+  claimGift: async (token: string, email: string): Promise<GiftClaimResult> => {
+    const response = await apiClient.post(`/cabinet/landing/gift/${token}/claim`, { email });
+    return response.data;
+  },
 };
 
 export interface LandingDailyStat {