feat: add LIMITED subscription status support with traffic-exhausted UX

- Add is_limited to Subscription type
- Show yellow traffic-exhausted badge on Subscription and AdminUsers pages
- SubscriptionCardExpired: amber theme with warning icon and buy-traffic CTA for limited
- Dashboard: route limited subscriptions to SubscriptionCardExpired
- Subscription page: show additional options (buy traffic) for limited subs
- Use is_limited boolean instead of status string comparison
- Add trafficLimited translations for ru, en, zh, fa
- AdminUserDetail StatusBadge: add limited yellow styling

src/locales/en.json

@@ -171,6 +171,7 @@
     "telegramRetryFailed": "Authorization failed. Close the app and try again.",
     "telegramReopenHint": "If the problem persists, close and reopen the app",
     "telegramNotConfigured": "Telegram bot is not configured",
+    "telegramUnavailable": "Telegram login is temporarily unavailable",
     "authenticating": "Authenticating...",
     "orOpenInApp": "Or open the bot in the app",
     "loginFailed": "Login Failed",
@@ -290,6 +291,9 @@
     "inactive": "Inactive",
     "trialStatus": "Trial",
     "expired": "Expired",
+    "trafficLimited": "Traffic Exhausted",
+    "trafficLimitedTitle": "Traffic Limit Reached",
+    "trafficLimitedDescription": "Your traffic has been exhausted. Purchase additional traffic below to continue using VPN.",
     "expiresAt": "Expires at",
     "daysLeft": "Days left",
     "devices": "Devices",