feat(runner): implement empty classroom sync functionality

Add support for fetching and synchronizing empty classroom data. This includes new protobuf definitions for task payloads and results, database models, repository, service, and HTTP handlers.

- Add `TASK_TYPE_GET_EMPTY_CLASSROOM` to `TaskType` enum
- Implement `EmptyClassroom` model and auto-migration
- Add `EmptyClassroomHandler` with `GET` and `POST /sync` routes
- Implement `EmptyClassroomSyncService` and `EmptyClassroomRepository`
- Update dependency injection with wire sets

internal/wire/service.go

@@ -48,6 +48,7 @@ var ServiceSet = wire.NewSet(
 	ProvideScheduleSyncService,
 		ProvideGradeSyncService,
 		ProvideExamSyncService,
+		ProvideEmptyClassroomSyncService,
 	ProvideGroupService,
 	ProvideUploadService,
 	ProvideUserActivityService,
@@ -263,6 +264,15 @@ func ProvideExamSyncService(
 	return service.NewExamSyncService(taskManager, examRepo, logger)
 }
 
+// ProvideEmptyClassroomSyncService 提供空教室同步服务
+func ProvideEmptyClassroomSyncService(
+	taskManager *runner.TaskManager,
+	classroomRepo repository.EmptyClassroomRepository,
+	logger *zap.Logger,
+) service.EmptyClassroomSyncService {
+	return service.NewEmptyClassroomSyncService(taskManager, classroomRepo, logger)
+}
+
 // ProvideGroupService 提供群组服务
 func ProvideGroupService(
 	groupRepo repository.GroupRepository,