fix: 修复 Flutter Web 白屏问题

- main.dart: 添加全局错误处理和 FlutterError.onError
- index.html: 添加加载指示器，vconsole 仅在开发环境启用
- dio_client.dart: 添加详细错误日志，优化超时配置

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

flutter_monisuo/lib/main.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:shadcn_ui/shadcn_ui.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
@@ -21,13 +22,37 @@ import 'ui/pages/auth/login_page.dart';
 import 'ui/pages/main/main_page.dart';
 
 void main() async {
+  // 确保 Flutter 绑定初始化
   WidgetsFlutterBinding.ensureInitialized();
-  Provider.debugCheckInvalidValueType = null;
 
-  await SharedPreferences.getInstance();
-  await LocalStorage.init();
+  // 全局错误处理
+  FlutterError.onError = (FlutterErrorDetails details) {
+    FlutterError.presentError(details);
+    debugPrint('Flutter Error: ${details.exception}');
+    debugPrint('Stack trace: ${details.stack}');
+  };
 
-  runApp(const MyApp());
+  // 捕获异步错误
+  runZonedGuarded<Future<void>>(
+    () async {
+      Provider.debugCheckInvalidValueType = null;
+
+      try {
+        await SharedPreferences.getInstance();
+        await LocalStorage.init();
+        debugPrint('App initialized successfully');
+      } catch (e, stack) {
+        debugPrint('Initialization error: $e');
+        debugPrint('Stack: $stack');
+      }
+
+      runApp(const MyApp());
+    },
+    (error, stack) {
+      debugPrint('Uncaught error: $error');
+      debugPrint('Stack: $stack');
+    },
+  );
 }
 
 class MyApp extends StatelessWidget {