feat: 完善听力口语辅助状态记录、练习分块与复习抽查间隔机制

kouyu_english/lib/main.dart

@@ -11,9 +11,7 @@ import 'features/shell/learning_shell.dart';
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
-  await SystemChrome.setPreferredOrientations([
-    DeviceOrientation.portraitUp,
-  ]);
+  await SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp]);
   // A0 is the offline baseline; the later levels load with the app state.
   await CourseRepository.instance.load(levels: {'A0'});
   runApp(const KouyuEnglishApp());