fix：商城登录互通问题

lib/features/mall/data/mall_auth_api.dart

@@ -1,3 +1,5 @@
+import 'dart:typed_data';
+
 import 'package:dio/dio.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 
@@ -25,17 +27,25 @@ class MallAuthApi {
   Future<AppMallAuthToken> issueAppMallAuthToken() async {
     final response = await _dio.post<List<int>>(
       '/api/v1/auth/mall/app-token',
-      data: const <int>[],
+      // Dio serializes a List<int> as the UTF-8 text "[]". This endpoint
+      // expects an empty protobuf message, whose wire representation is zero
+      // bytes; Uint8List keeps the request body binary and untransformed.
+      data: Uint8List(0),
       options: protobufOptions(),
     );
     final reply = ProtoMessage(response.data ?? const <int>[]);
     final token = reply.string(1).trim();
-    if (token.isEmpty) throw const FormatException('Missing mall auth token');
+    final expiresIn = reply.integer(2);
+    final sourceApp = reply.string(3).trim();
+    final scene = reply.string(4).trim();
+    if (token.isEmpty || expiresIn <= 0 || sourceApp.isEmpty || scene.isEmpty) {
+      throw const FormatException('Incomplete mall auth token response');
+    }
     return AppMallAuthToken(
       authToken: token,
-      expiresIn: reply.integer(2),
-      sourceApp: reply.string(3),
-      scene: reply.string(4),
+      expiresIn: expiresIn,
+      sourceApp: sourceApp,
+      scene: scene,
     );
   }
 }