refactor: 移除 macOS 平台特定的窗口大小设置代码

该功能已不再需要，因此清理相关代码以简化主函数

lib/main.dart

@@ -10,8 +10,6 @@ import 'package:flutter_screenutil/flutter_screenutil.dart';
 import 'core/bindings/initial_binding.dart';
 import 'routes/app_pages.dart';
 import 'routes/app_routes.dart';
-import 'dart:io';
-import 'package:window_size/window_size.dart';
 import 'core/translations/app_translations.dart';
 import 'core/themes/app_theme.dart';
 import 'core/themes/theme_service.dart';
@@ -32,28 +30,6 @@ void main() async {
   // 初始化登录服务（包含Firebase初始化）
   LoginService();
 
-  // 设置窗口大小（仅在 macOS 下生效）
-  if (Platform.isMacOS) {
-    const double width = 375.0;
-    const double height = 812.0;
-
-    setWindowTitle('Voitrans');
-    setWindowMinSize(const Size(width, height));
-    setWindowMaxSize(const Size(width, height));
-
-    // 居中显示窗口
-    final screen = await getCurrentScreen();
-    if (screen != null) {
-      final screenFrame = screen.frame;
-      final windowFrame = Rect.fromCenter(
-        center: screenFrame.center,
-        width: width,
-        height: height,
-      );
-      setWindowFrame(windowFrame);
-    }
-  }
-
   // 运行应用
   runApp(const MainApp());
 }