feat: 任务列表显示 turn_id 与 root_turn_id

host.py dispatch 打印补 turn_id/root_turn_id；执行器解析（local/Docker）透传；worker 写回 tasks 新列（新值非空才覆盖）；server 迁移与接口字段；控制台任务列表新增 turn/root turn 两列（短显+悬停全文）；新单测 9 个。

host.py

@@ -2373,6 +2373,8 @@ def main():
                               "cwd": task["cwd"], "status": task["status"],
                               "text": result.get("text", ""),
                               "error": result.get("error"),
+                              "turn_id": result.get("turn_id"),
+                              "root_turn_id": result.get("root_turn_id"),
                               "usage": result.get("usage")},
                              indent=2, ensure_ascii=False))
         elif args.cmd == "list":