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/locales/en.json

@@ -4834,6 +4834,34 @@
     "merging": "Merging..."
   },
   "landing": {
+    "giftClaim": {
+      "title": "You have a gift!",
+      "error": "Could not activate the gift.",
+      "notFoundTitle": "Gift not found",
+      "notFoundDesc": "This gift link is invalid or no longer available.",
+      "alreadyTitle": "Gift already activated",
+      "alreadyDesc": "This gift has already been claimed.",
+      "successTitle": "Gift activated!",
+      "connectDesc": "Use this link to connect:",
+      "copyLink": "Copy link",
+      "pendingTitle": "Almost ready…",
+      "pendingDesc": "The payment is still being confirmed. This page will update automatically.",
+      "replaceWarning": "You already have a subscription — activating this gift will replace it.",
+      "activateTelegram": "Activate in Telegram",
+      "activateWeb": "Activate by email",
+      "emailLabel": "Your email",
+      "claimNow": "Get my gift"
+    },
+    "giftLink": {
+      "shareText": "I have a gift for you! Activate it here:",
+      "viaTelegram": "Telegram:",
+      "title": "Gift is ready!",
+      "subtitle": "Send this link to whoever you want to receive the gift — they activate it themselves.",
+      "linkLabel": "Gift link",
+      "telegramLabel": "Telegram link",
+      "alsoSent": "We also emailed it to {{contact}}.",
+      "copyMessage": "Copy message"
+    },
     "notFound": "Page not found",
     "forMe": "For me",
     "asGift": "As a gift",

src/locales/fa.json

@@ -4494,6 +4494,34 @@
     "merging": "در حال ادغام..."
   },
   "landing": {
+    "giftClaim": {
+      "title": "شما یک هدیه دارید!",
+      "error": "فعال‌سازی هدیه ناموفق بود.",
+      "notFoundTitle": "هدیه یافت نشد",
+      "notFoundDesc": "این لینک هدیه نامعتبر یا دیگر در دسترس نیست.",
+      "alreadyTitle": "هدیه قبلاً فعال شده است",
+      "alreadyDesc": "این هدیه قبلاً دریافت شده است.",
+      "successTitle": "هدیه فعال شد!",
+      "connectDesc": "از این لینک برای اتصال استفاده کنید:",
+      "copyLink": "کپی لینک",
+      "pendingTitle": "تقریباً آماده است…",
+      "pendingDesc": "پرداخت در حال تأیید است. این صفحه به‌طور خودکار به‌روزرسانی می‌شود.",
+      "replaceWarning": "شما در حال حاضر اشتراک دارید — فعال‌سازی این هدیه جایگزین آن خواهد شد.",
+      "activateTelegram": "فعال‌سازی در تلگرام",
+      "activateWeb": "فعال‌سازی با ایمیل",
+      "emailLabel": "ایمیل شما",
+      "claimNow": "دریافت هدیه"
+    },
+    "giftLink": {
+      "shareText": "یک هدیه برای شما دارم! اینجا فعال کنید:",
+      "viaTelegram": "تلگرام:",
+      "title": "هدیه آماده است!",
+      "subtitle": "این لینک را برای کسی که می‌خواهید هدیه را دریافت کند بفرستید — خودش آن را فعال می‌کند.",
+      "linkLabel": "لینک هدیه",
+      "telegramLabel": "لینک تلگرام",
+      "alsoSent": "آن را به {{contact}} نیز ایمیل کردیم.",
+      "copyMessage": "کپی پیام"
+    },
     "notFound": "صفحه یافت نشد",
     "forMe": "برای خودم",
     "asGift": "به عنوان هدیه",

src/locales/ru.json

@@ -5389,6 +5389,34 @@
     "merging": "Объединение..."
   },
   "landing": {
+    "giftClaim": {
+      "title": "Вам подарок!",
+      "error": "Не удалось активировать подарок.",
+      "notFoundTitle": "Подарок не найден",
+      "notFoundDesc": "Ссылка на подарок недействительна или больше недоступна.",
+      "alreadyTitle": "Подарок уже активирован",
+      "alreadyDesc": "Этот подарок уже забрали.",
+      "successTitle": "Подарок активирован!",
+      "connectDesc": "Используйте эту ссылку для подключения:",
+      "copyLink": "Скопировать ссылку",
+      "pendingTitle": "Почти готово…",
+      "pendingDesc": "Оплата ещё подтверждается. Страница обновится автоматически.",
+      "replaceWarning": "У вас уже есть подписка — активация подарка заменит её.",
+      "activateTelegram": "Активировать в Telegram",
+      "activateWeb": "Активировать по почте",
+      "emailLabel": "Ваш email",
+      "claimNow": "Получить подарок"
+    },
+    "giftLink": {
+      "shareText": "Дарю вам подписку! Активируйте здесь:",
+      "viaTelegram": "Telegram:",
+      "title": "Подарок готов!",
+      "subtitle": "Отправьте эту ссылку тому, кому предназначен подарок — он активирует его сам.",
+      "linkLabel": "Ссылка на подарок",
+      "telegramLabel": "Ссылка для Telegram",
+      "alsoSent": "Мы также отправили её на {{contact}}.",
+      "copyMessage": "Скопировать сообщение"
+    },
     "notFound": "Страница не найдена",
     "forMe": "Для себя",
     "asGift": "В подарок",

src/locales/zh.json

@@ -4493,6 +4493,34 @@
     "merging": "合并中..."
   },
   "landing": {
+    "giftClaim": {
+      "title": "您收到一份礼物！",
+      "error": "无法激活礼物。",
+      "notFoundTitle": "未找到礼物",
+      "notFoundDesc": "此礼物链接无效或已不可用。",
+      "alreadyTitle": "礼物已激活",
+      "alreadyDesc": "此礼物已被领取。",
+      "successTitle": "礼物已激活！",
+      "connectDesc": "使用此链接连接：",
+      "copyLink": "复制链接",
+      "pendingTitle": "即将完成…",
+      "pendingDesc": "付款仍在确认中。本页面将自动更新。",
+      "replaceWarning": "您已有订阅——激活此礼物将替换它。",
+      "activateTelegram": "在 Telegram 中激活",
+      "activateWeb": "通过邮箱激活",
+      "emailLabel": "您的邮箱",
+      "claimNow": "领取礼物"
+    },
+    "giftLink": {
+      "shareText": "我送您一份订阅！在此激活：",
+      "viaTelegram": "Telegram：",
+      "title": "礼物已就绪！",
+      "subtitle": "将此链接发送给您想赠送的人——他们自行激活。",
+      "linkLabel": "礼物链接",
+      "telegramLabel": "Telegram 链接",
+      "alsoSent": "我们也已发送到 {{contact}}。",
+      "copyMessage": "复制消息"
+    },
     "notFound": "页面未找到",
     "forMe": "为自己",
     "asGift": "作为礼物",