Fix BrowserView cleanup on component unmount

- Separate BrowserView cleanup into dedicated useEffect with empty dependency array
- Ensures cleanup runs when WebViewer component is unmounted, not just on URL changes
- Add detailed logging for debugging BrowserView destruction
- Fixes issue where BrowserView persists after closing WebViewer container
- Proper cleanup prevents orphaned BrowserView instances floating on screen

ui/desktop/src/components/WebViewer.tsx

@@ -152,15 +152,23 @@ export function WebViewer({
       }
     }, 100);
 
-    // Cleanup on unmount
     return () => {
       clearTimeout(timer);
-      if (browserViewCreated && browserViewId.current) {
-        window.electron.destroyBrowserView(browserViewId.current).catch(console.error);
-      }
     };
   }, [url]);
 
+  // Cleanup BrowserView on component unmount
+  useEffect(() => {
+    return () => {
+      console.log('WebViewer component unmounting, cleaning up BrowserView:', browserViewId.current);
+      if (browserViewId.current) {
+        window.electron.destroyBrowserView(browserViewId.current).catch((err) => {
+          console.error('Error destroying BrowserView on unmount:', err);
+        });
+      }
+    };
+  }, []);
+
   // Update BrowserView bounds when container resizes
   useEffect(() => {
     if (!browserViewCreated || !containerRef.current) return;