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/shared/widgets/back_title_page_header.dart

@@ -0,0 +1,65 @@
+import 'package:flutter/material.dart';
+
+import '../../core/theme/design_tokens.dart';
+import 'page_header.dart' as widgets;
+
+class BackTitlePageHeader extends StatelessWidget {
+  const BackTitlePageHeader({
+    super.key,
+    required this.title,
+    this.onBack,
+    this.showBackButton = true,
+    this.trailing,
+    this.height = 64,
+  });
+
+  final String title;
+  final VoidCallback? onBack;
+  final bool showBackButton;
+  final Widget? trailing;
+  final double height;
+
+  @override
+  Widget build(BuildContext context) {
+    return SizedBox(
+      height: height,
+      child: Stack(
+        alignment: Alignment.center,
+        children: [
+          widgets.PageHeader(
+            leading: showBackButton
+                ? widgets.BackButton(onPressed: onBack)
+                : const SizedBox(
+                    width: AppSpacing.xl * 2,
+                    height: AppSpacing.xl * 2,
+                  ),
+            trailing:
+                trailing ??
+                const SizedBox(
+                  width: AppSpacing.xl * 2,
+                  height: AppSpacing.xl * 2,
+                ),
+            height: height,
+          ),
+          IgnorePointer(
+            child: Padding(
+              padding: const EdgeInsets.symmetric(
+                horizontal: AppSpacing.xxl * 2,
+              ),
+              child: Text(
+                title,
+                maxLines: 1,
+                overflow: TextOverflow.ellipsis,
+                style: const TextStyle(
+                  fontSize: 18,
+                  fontWeight: FontWeight.w700,
+                  color: AppColors.slate900,
+                ),
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}