Fix: Add cleanup on component unmount

- Close all connections when component unmounts
- Prevents polling timers from running after unmount
- Better resource cleanup

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/App.jsx

@@ -71,6 +71,14 @@ export default function App() {
     }
   }, []);
 
+  // Cleanup on unmount
+  useEffect(() => {
+    return () => {
+      // Close all connections when component unmounts
+      myConnections.forEach(c => c.conn?.close());
+    };
+  }, [myConnections]);
+
   // Register
   const handleRegister = async () => {
     if (!client) return;