feat(client): 登录模块对接后端 API

- auth_state: 增加 refreshToken 字段 + flutter_secure_storage 持久化
- api_client: 增加 401 自动 refresh + retry 拦截器
- auth_repository: 封装 POST /api/v1/auth/login 调用，错误信息本地化
- login_screen: 增加门店编号字段，调真实 API，行内错误展示
- main: 启动时 restore 持久化登录态，避免每次重启都要重新登录
- 修复 app_shell: hotelName → hotelNo
- 修复 widget_test: 移除失效的占位测试

测试账号：门店编号 H001 / 用户名 admin / 密码 password123

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

client/lib/main.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'core/auth/auth_state.dart';
 import 'core/router/app_router.dart';
 import 'core/theme/app_theme.dart';
 
@@ -10,6 +11,51 @@ void main() {
 class JiuApp extends ConsumerWidget {
   const JiuApp({super.key});
 
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    return MaterialApp(
+      title: '酒库管理系统',
+      theme: AppTheme.light(),
+      debugShowCheckedModeBanner: false,
+      home: const _AppBootstrap(),
+    );
+  }
+}
+
+/// Restores persisted auth before handing off to the router.
+class _AppBootstrap extends ConsumerStatefulWidget {
+  const _AppBootstrap();
+
+  @override
+  ConsumerState<_AppBootstrap> createState() => _AppBootstrapState();
+}
+
+class _AppBootstrapState extends ConsumerState<_AppBootstrap> {
+  bool _ready = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _init();
+  }
+
+  Future<void> _init() async {
+    await ref.read(authStateProvider.notifier).restore();
+    if (mounted) setState(() => _ready = true);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (!_ready) {
+      return const Scaffold(
+        body: Center(child: CircularProgressIndicator()),
+      );
+    }
+    return _RouterApp();
+  }
+}
+
+class _RouterApp extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final router = ref.watch(appRouterProvider);