feat: migrate Telegram Login Widget to v23 with admin-configurable settings

- Upgrade telegram-widget.js from v22 to v23 (TelegramLoginButton + ConnectedAccounts)
- TelegramLoginButton fetches widget config from API instead of hardcoded values
- Add TelegramWidgetConfig type and API method with fallback to env defaults
- Remove botUsername prop — now sourced from backend API
- Add useEffect cleanup to prevent orphaned iframes on unmount
- Add TELEGRAM_WIDGET category to admin interface settings menu
- Add i18n translations for widget settings (ru, en, zh, fa)

src/components/admin/constants.ts

@@ -67,6 +67,7 @@ export const MENU_SECTIONS: MenuSection[] = [
           'INTERFACE_SUBSCRIPTION',
           'CONNECT_BUTTON',
           'MINIAPP',
+          'TELEGRAM_WIDGET',
           'HAPP',
           'SKIP',
           'ADDITIONAL',