fix: token过期自动跳转登录页

- dio_client.dart: 401错误时触发onUnauthorized回调
- main.dart: 连接回调到AuthProvider.forceLogout
- 完整链路: 401 -> 清除token -> 强制登出 -> 显示LoginPage

flutter_monisuo/lib/core/network/dio_client.dart

@@ -17,6 +17,9 @@ class NetworkConfig {
 class DioClient {
   late final Dio _dio;
 
+  /// 未授权回调（token 过期时触发）
+  VoidCallback? onUnauthorized;
+
   DioClient() {
     _dio = _createDio();
     _setupInterceptors();
@@ -92,7 +95,13 @@ class DioClient {
   ) {
     final data = response.data;
     if (data is Map<String, dynamic>) {
-      return ApiResponse.fromJson(data, fromJson);
+      final apiResponse = ApiResponse.fromJson(data, fromJson);
+      // 检测业务层未授权（后端返回 HTTP 200 + code "0002"）
+      if (apiResponse.isUnauthorized) {
+        LocalStorage.clearUserData();
+        onUnauthorized?.call();
+      }
+      return apiResponse;
     }
     return ApiResponse.fail('响应数据格式错误');
   }
@@ -109,6 +118,7 @@ class DioClient {
 
     if (_isUnauthorized(e)) {
       _clearUserData();
+      onUnauthorized?.call();
       return ApiResponse.unauthorized('登录已过期，请重新登录');
     }