Change `items` to `stuff`

I may have foolishly decided to call the db, `items` and stick to that naming convention in the code. Might collide with some python stuff. IDK, IDK python. Would be good to come up with something else. Perhaps, "choms?"

未指定文件、测试或入口点。首先在仓库中查找对 `items` 的引用，并确定重命名的范围；在开始工作之前，需要由维护者决定替换名称。完成的标准是：所选命名约定得到一致应用，同时不会破坏数据库或 Python 代码。

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