期望 Bubble.List 组件支持虚拟滚动

### 需求动机

目前当数据量大的setItem的时候，DOM在不停的添加到容器中，导致撑开容器Y轴滚动条也不停的变小，deepseek或者chatGPT在加载历史消息的时候不会出现这种情况

### 提议的 API 是什么样的？

_No response_

Start by locating the Bubble.List component and tracing how setItem adds large data sets to the container. Compare its current behavior with the reported history-message use case, then define completion as virtual scrolling that prevents the container's Y-axis scrollbar from continually shrinking while large data sets load.

Written by the indexing model from the issue text.