fix(macos): initialize file picker for non-sandboxed windows

ui/flutter/lib/main.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 
 import 'package:app_links/app_links.dart';
+import 'package:file_picker/file_picker.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_foreground_task/flutter_foreground_task.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
@@ -17,6 +18,11 @@ import 'util/util.dart';
 
 Future<void> main(List<String> args) async {
   WidgetsFlutterBinding.ensureInitialized();
+  if (Util.isMacos()) {
+    // Gopeed is not sandboxed. Configure each engine before the main/child
+    // window split so native file and directory dialogs work in both windows.
+    await FilePicker.skipEntitlementsChecks();
+  }
   if (Util.isAndroid()) {
     FlutterForegroundTask.initCommunicationPort();
   }