feat: add school authentication entry with guarded import

mobile/lib/app/hepan_app.dart

@@ -5,24 +5,36 @@ import 'app_theme.dart';
 import '../widgets/glass_dock.dart';
 import '../features/timetable/timetable_page.dart';
 import '../features/profile/profile_page.dart';
+import '../features/school/school_session.dart';
 
 class HepanApp extends StatelessWidget {
-  const HepanApp({super.key, required this.controller, this.schoolBuilder});
+  const HepanApp({
+    super.key,
+    required this.controller,
+    this.schoolBuilder,
+    this.school,
+  });
   final AppController controller;
   final Widget Function()? schoolBuilder;
+  final SchoolSession? school;
   @override
   Widget build(BuildContext context) => MaterialApp(
     debugShowCheckedModeBanner: false,
     title: '河畔Everyday',
     theme: hepanTheme(),
-    home: _Shell(controller: controller, schoolBuilder: schoolBuilder),
+    home: _Shell(
+      controller: controller,
+      schoolBuilder: schoolBuilder,
+      school: school,
+    ),
   );
 }
 
 class _Shell extends StatefulWidget {
-  const _Shell({required this.controller, this.schoolBuilder});
+  const _Shell({required this.controller, this.schoolBuilder, this.school});
   final AppController controller;
   final Widget Function()? schoolBuilder;
+  final SchoolSession? school;
   @override
   State<_Shell> createState() => _ShellState();
 }
@@ -71,9 +83,41 @@ class _ShellState extends State<_Shell> with WidgetsBindingObserver {
     }
   }
 
+  Future<void> _logout() async {
+    final choice = await showDialog<int>(
+      context: context,
+      builder: (context) => AlertDialog(
+        title: const Text('退出学校登录'),
+        content: const Text('已导入的课表是否保留在手机中？'),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(context, 0),
+            child: const Text('取消'),
+          ),
+          TextButton(
+            onPressed: () => Navigator.pop(context, 1),
+            child: const Text('保留课表'),
+          ),
+          TextButton(
+            onPressed: () => Navigator.pop(context, 2),
+            child: const Text('清除课表'),
+          ),
+        ],
+      ),
+    );
+    if (choice == null || choice == 0) return;
+    await widget.school?.logout();
+    if (choice == 2) {
+      await widget.controller.clearCourses();
+    }
+  }
+
   @override
   Widget build(BuildContext context) => AnimatedBuilder(
-    animation: widget.controller,
+    animation: Listenable.merge([
+      widget.controller,
+      if (widget.school != null) widget.school!,
+    ]),
     builder: (context, _) => Scaffold(
       body: Container(
         decoration: const BoxDecoration(
@@ -118,6 +162,10 @@ class _ShellState extends State<_Shell> with WidgetsBindingObserver {
                           ProfilePage(
                             controller: widget.controller,
                             onLogin: _school,
+                            authStatus: widget.school?.statusLabel ?? '未登录',
+                            onLogout: widget.school?.hasOpened == true
+                                ? _logout
+                                : null,
                           ),
                         ],
                       ),