补全 services/tjnetwork.py 的 Facade 覆盖，把绕过的 8 处直接引用都收归到 tjnetwork.py 导出

app/api/v1/endpoints/snapshots.py

@@ -1,6 +1,6 @@
 from fastapi import APIRouter, Request
-from app.native.wndb import ChangeSet
 from app.services.tjnetwork import (
+    ChangeSet,
     get_current_operation,
     execute_undo,
     execute_redo,