feat: ui improvement

flutter 3.7 compatibility
responsive view
beautiful progress bar
select file in treeview
downlading and downloaded page

ui/flutter/lib/pages/create/create_controller.dart

@@ -1,3 +1,6 @@
 import 'package:get/get.dart';
 
-class CreateController extends GetxController {}
+class CreateController extends GetxController {
+  final files = [].obs;
+  final RxList selectedIndexs = [].obs;
+}