fix：商城登录互通问题

lib/features/auth/presentation/login_page.dart

@@ -47,11 +47,19 @@ class LoginPage extends HookConsumerWidget {
     Future<void> returnAfterLogin() async {
       final target = next?.trim();
       final router = GoRouter.of(context);
-      if (target == null || target.isEmpty) {
-        router.go(AppRoutes.profile);
+      if (target != null && target.isNotEmpty) {
+        router.go(target);
         return;
       }
-      router.go(target);
+      // The mall opens this page with no `next`. Pop back to its resident
+      // WebView so the auth-state listener can deliver `enterWebMall` after
+      // the app-mall token has been issued. Replacing the route here disposes
+      // that WebView before the asynchronous hand-off can finish.
+      if (context.canPop()) {
+        context.pop();
+      } else {
+        router.go(AppRoutes.profile);
+      }
     }
 
     void startCountdown() {

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,
     );
   }
 }