feat: 实现 Auth 全局状态机与 401 统一处理机制

- 新增 AuthSessionInvalidated 事件处理 token 失效场景
- ApiInterceptor 新增 authFailureCallback 单飞机制
- AuthBloc 区分 manual logout 与 auto expiry 语义
- 新增 startup recovery fallback 防止启动卡死

feat: 重构 Calendar DayWeek 视图事件布局引擎

- 新增 DayEventLayoutEngine 解耦事件计算与渲染
- 新增 DayTimelineMetrics 统一时间轴常量
- 新增 DayViewScale 支持捏合缩放

feat: 新增 Settings 页面共享 UI 组件

- 新增 BackTitlePageHeader 统一页面 header
- 新增 DetailHeaderActionMenu 统一操作菜单
- 新增 DestructiveActionSheet 统一删除确认
- 新增 AppToggleSwitch 统一开关组件

feat: Chat UI Schema 支持导航操作

- 支持 navigation 类型 action 触发内部路由跳转
- 新增路径验证与参数处理

chore: 更新相关测试覆盖 auth 失效路径

apps/lib/features/contacts/ui/screens/add_contact_screen.dart

@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 import '../../../../core/theme/design_tokens.dart';
-import '../../../../shared/widgets/page_header.dart' as widgets;
+import '../../../../shared/widgets/back_title_page_header.dart';
 import '../../../../shared/widgets/app_input.dart';
 import '../../../../shared/widgets/link_button.dart';
 import '../../../../shared/widgets/toast/toast.dart';
@@ -37,15 +37,18 @@ class _AddContactScreenState extends State<AddContactScreen> {
       backgroundColor: AppColors.surfaceSecondary,
       body: SafeArea(
         child: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
           children: [
-            widgets.PageHeader(
-              leading: widgets.BackButton(),
+            BackTitlePageHeader(
+              title: isEditing ? '编辑联系人' : '添加联系人',
+              onBack: () => context.pop(),
               trailing: _buildConfirmButton(),
             ),
             Expanded(
               child: SingleChildScrollView(
                 padding: const EdgeInsets.fromLTRB(20, 8, 20, 20),
                 child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.stretch,
                   children: [
                     _buildAvatarSection(),
                     const SizedBox(height: 14),

apps/lib/features/contacts/ui/screens/contacts_screen.dart

@@ -5,7 +5,7 @@ import '../../../../core/theme/design_tokens.dart';
 import '../../../../shared/widgets/app_loading_indicator.dart';
 import '../../../../shared/widgets/toast/index.dart';
 import '../../../../shared/widgets/app_button.dart';
-import '../../../../shared/widgets/page_header.dart' as widgets;
+import '../../../../shared/widgets/back_title_page_header.dart';
 import '../../../friends/data/friends_api.dart';
 import '../../../users/data/models/user_response.dart';
 import '../../../users/data/users_api.dart';
@@ -267,8 +267,9 @@ class _ContactsScreenState extends State<ContactsScreen> {
       backgroundColor: AppColors.surfaceSecondary,
       body: SafeArea(
         child: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
           children: [
-            widgets.PageHeader(leading: widgets.BackButton()),
+            BackTitlePageHeader(title: '联系人', onBack: () => context.pop()),
             Expanded(
               child: SingleChildScrollView(
                 padding: const EdgeInsets.fromLTRB(20, 8, 20, 20),