fix: single ESC exits both immersive overlay and window fullscreen

closeFullScreen() now also exits window fullscreen so the user
doesn't need to press ESC twice.

cc

src/lib/stores/uiStore.ts

@@ -149,6 +149,9 @@ export function openFullScreen(): void {
 
 export function closeFullScreen(): void {
   isFullScreenOpen = false;
+  getCurrentWindow().isFullscreen().then(fs => {
+    if (fs) getCurrentWindow().setFullscreen(false);
+  });
   notifyListeners();
 }