fix(frontend): gate credits API calls behind buyCredits feature flag

The backend returns 404 for /credits/summary and /credits/batches/expiring
when BUY_CREDITS_ACTIVE is disabled. SessionEnsurer was polling /credits/summary
every 30 s and ExpiryWarningBanner was polling /credits/batches/expiring every
5 min for all authenticated users, flooding the console with 404 errors and
adding unnecessary network overhead.

Both queries now use `enabled: !!session?.data && !!features?.buyCredits` so
they only fire when the feature flag is actually on. ExpiryWarningBanner also
gains the useUserStore import needed to read the flag.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: EmilFattakhov

apps/frontend/src/components/atoms/ExpiryWarningBanner.tsx

@@ -11,6 +11,7 @@ import {
   sumExpiringUploadBytes,
 } from '../../utils/credits';
 import { BannerShell } from '../organisms/BannerNotifications/BannerShell';
+import { useUserStore } from '../../globalStates/user';
 
 /**
  * Displays a warning banner when the user has purchased credits that will
@@ -20,13 +21,16 @@ import { BannerShell } from '../organisms/BannerNotifications/BannerShell';
 export const ExpiryWarningBanner = () => {
   const { api } = useNetwork();
   const session = useContext(SessionContext);
+  const features = useUserStore((m) => m.features);
 
   const { data: expiringBatches } = useQuery<ExpiringCreditBatch[]>({
     queryKey: ['expiringCreditBatches'],
     queryFn: () => api.getExpiringCreditBatches(),
     // Refresh every 5 minutes – expiry warnings don't need to be real-time
     refetchInterval: 5 * 60 * 1000,
-    enabled: !!session?.data,
+    // Only fetch when the buyCredits feature flag is enabled – the backend
+    // returns 404 for these endpoints when the flag is off.
+    enabled: !!session?.data && !!features?.buyCredits,
   });
 
   if (!expiringBatches || expiringBatches.length === 0) return null;

apps/frontend/src/components/atoms/SessionEnsurer.tsx

@@ -61,7 +61,9 @@ export const SessionEnsurer = ({ children }: { children: React.ReactNode }) => {
     queryFn: () => api.getCreditSummary(),
     // Refresh every 30 s so the cap / balance stays reasonably fresh
     refetchInterval: 30_000,
-    enabled: !!session?.data,
+    // Only fetch when the buyCredits feature flag is enabled – the backend
+    // returns 404 for these endpoints when the flag is off.
+    enabled: !!session?.data && !!features?.buyCredits,
   });
 
   const { data: touStatusData, isLoading: touStatusLoading } = useQuery({