优化结构

internal/biz/system/maintenance.go

@@ -0,0 +1,19 @@
+package system
+
+import "context"
+
+// MaintenanceRepo owns retention work for system-owned tables. Other data
+// modules clean their own tables and worker composes the operations.
+type MaintenanceRepo interface {
+	CleanupExpired(context.Context) error
+}
+
+type MaintenanceUsecase struct{ repo MaintenanceRepo }
+
+func NewMaintenanceUsecase(repo MaintenanceRepo) *MaintenanceUsecase {
+	return &MaintenanceUsecase{repo: repo}
+}
+
+func (uc *MaintenanceUsecase) CleanupExpired(ctx context.Context) error {
+	return uc.repo.CleanupExpired(ctx)
+}