同步更新：重构路由、服务模块，更新前端构建

services/checkpoints.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+from __future__ import annotations
+
+from typing import Optional
+
+from task_checkpoint import TaskStage, get_checkpoint_manager
+
+_checkpoint_mgr = None  # type: Optional[object]
+
+
+def init_checkpoint_manager():
+    global _checkpoint_mgr
+    if _checkpoint_mgr is None:
+        _checkpoint_mgr = get_checkpoint_manager()
+    return _checkpoint_mgr
+
+
+def get_checkpoint_mgr():
+    return init_checkpoint_manager()
+