🐛 `MenuFlyout` is immediately closed on iOS

**Describe the bug**
Attempting to use a `FlyoutController` to show a `MenuFlyout` does not work on iOS. You can occasionally see what I believe is the flyout appearing for a frame or two before going away. Otherwise, a button that shows a `MenuFlyout` usually looks like it isn't showing any flyout at all. The flyout controller can show other widgets as flyouts (e.g., just a `Text`).

**Additional context**
`MenuFlyout` works just fine on Windows, Android, Web, and MacOS (I have verified with the snippet below).

**To Reproduce**
Snippet to reproduce:
```dart
import 'package:fluent_ui/fluent_ui.dart';

void main() {
WidgetsFlutterBinding.ensureInitialized();
runApp(MainApp());
}

class MainApp extends StatelessWidget {
MainApp({super.key});

final controller = FlyoutController();

@override
Widget build(BuildContext context) {
return FluentApp(
home: ScaffoldPage(
content: Center(
child: FlyoutTarget(
controller: controller,
child: IconButton(
icon: Icon(FluentIcons.activity_feed),
onPressed: () {
controller.showFlyout(
builder: (context) {
// TODO: Uncomment to see this work fine.
// return Text('This works fine');

return MenuFlyout(
items: [
MenuFlyoutItem(
text: Text('Option 1'),
onPressed: () {
print('Option 1 - pressed');
},
),
],
);
},
);
},
),
),
),
),
);
}
}
```

Start by running the provided Flutter snippet on iOS and compare the MenuFlyout behavior with the Text flyout, which remains visible. Trace the FlyoutController.showFlyout path and MenuFlyout rendering or dismissal behavior; done means the menu stays open on iOS and its item can be pressed, while existing platforms continue to work.

Written by the indexing model from the issue text.