ui refactor

client/src/App.tsx

@@ -12,6 +12,13 @@ const App: React.FC = () => {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
 
+  useEffect(() => {
+    if (error) {
+      const timer = setTimeout(() => setError(null), 5000);
+      return () => clearTimeout(timer);
+    }
+  }, [error]);
+
   useEffect(() => {
     loadTasks();
   }, []);