feat(网络拦截器): 添加请求签名和时间戳头

在请求头中添加时间戳和基于MD5的签名，与Go端保持一致的验证机制

lib/data/services/network/auth_interceptor.dart

@@ -1,20 +1,33 @@
 import 'package:dio/dio.dart';
 import 'package:flutter/material.dart';
 import 'package:get/get.dart' hide Response;
+import 'dart:convert';
+import 'package:crypto/crypto.dart';
 
 import 'package:get_storage/get_storage.dart';
 import 'entity/base_entity.dart';
 
 class AuthInterceptor extends Interceptor {
   final GetStorage _storage = GetStorage();
+  final String _signKey = '@214%67g15q4*67m17#4l67!'; // 替换为实际的密钥
 
   @override
   void onRequest(RequestOptions options, RequestInterceptorHandler handler) {
     var jsonString = _storage.read<String>("logintoken");
     options.headers['Authorization'] = jsonString;
+    final timestamp = DateTime.now().millisecondsSinceEpoch.toString();
+    options.headers['Ts'] = timestamp;
+    options.headers['Sign'] = _generateSign(timestamp);
     handler.next(options);
   }
 
+  String _generateSign(String timestamp) {
+    // 按照“MD5(私钥 + 时间戳)”生成签名，与 Go 端保持一致
+    final signStr = 'ts=${timestamp}key=${_signKey}';
+    print("signStr: $signStr");
+    return md5.convert(utf8.encode(signStr)).toString();
+  }
+
   @override
   void onResponse(Response response, ResponseInterceptorHandler handler) async {
     BaseEntity entity = BaseEntity.fromJson(response.data);