Fix race condition causing permissions error on /display page

onAuthStateChanged fires with null before signInAnonymously completes,
causing DisplayView to query Firestore unauthenticated. Now only marks
auth ready when an actual user is present; auth failures are handled in
the catch block to avoid hanging the UI.

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

src/App.js

@@ -2658,13 +2658,21 @@ function App() {
       } catch (err) {
         console.error("Authentication error:", err);
         setError("Failed to authenticate. Please try again later.");
+        // Auth failed and onAuthStateChanged won't fire with a user, so unblock the UI here
+        setIsAuthReady(true);
+        setIsLoading(false);
       }
     };
 
     const unsubscribe = onAuthStateChanged(auth, (user) => {
       setUserId(user ? user.uid : null);
+      // Only mark auth ready once we have an actual authenticated user.
+      // onAuthStateChanged fires with null before signInAnonymously completes,
+      // which would cause Firestore queries to run unauthenticated.
+      if (user) {
         setIsAuthReady(true);
         setIsLoading(false);
+      }
     });
 
     initAuth();