Auto-redirect to login on 401 API responses

When a session token expires, API calls return 401 but nothing caught
it — errors were shown as generic dialogs or swallowed. Now both
apiClient and streamingService detect 401 responses and clear auth
state, which causes App.tsx to render the login modal automatically.

frontend/src/App.tsx

@@ -18,6 +18,8 @@ import { Button } from './components/ui/button';
 import { Filter } from 'lucide-react';
 import type { GeoJSONFeatureCollection, PropertyProperties, PropertyFeature, POI, POITravelFilter } from '@/types';
 import { refreshListings, streamListingGeoJSON, fetchUserPOIs, type StreamingProgress } from '@/services';
+import { setOnUnauthorized } from '@/services/apiClient';
+import { clearPasskeyUser } from './auth/passkeyService';
 import { poiMetricPropertyName, injectPoiMetricProperty } from '@/utils/poiUtils';
 import { useTaskProgress } from '@/hooks/useTaskProgress';
 
@@ -94,6 +96,13 @@ function App() {
     }
   }, []);
 
+  useEffect(() => {
+    setOnUnauthorized(() => {
+      clearPasskeyUser();
+      setUser(null);
+    });
+  }, []);
+
   const handlePasskeyLogin = (passkeyUser: AuthUser) => {
     setUser(passkeyUser);
   };