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/pages/ConnectedAccounts.tsx

@@ -44,7 +44,7 @@ function TelegramLinkWidget() {
     const redirectUrl = `${window.location.origin}/auth/link/telegram/callback?csrf_state=${encodeURIComponent(csrfState)}`;
 
     const script = document.createElement('script');
-    script.src = 'https://telegram.org/js/telegram-widget.js?22';
+    script.src = 'https://telegram.org/js/telegram-widget.js?23';
     script.setAttribute('data-telegram-login', botUsername);
     script.setAttribute('data-size', 'small');
     script.setAttribute('data-radius', '8');