chat: AI 回答中的 LaTeX 公式未渲染,源码原样露出

AI 回答里的数学公式(`\[...\]` / `\(...\)` 定界的 LaTeX)未渲染:聊天页 markdown 渲染层没有数学语法支持,commonmark 解析还会吃掉 `\[` 的反斜杠,最终显示的是 `[ \frac{人数\times(人数-1)}{2} ]` 一类源码乱码。

2026-08-29 真机自测发现。

Start at the chat page's Markdown rendering layer and reproduce the issue with both \[...\] and \(...\) delimiters, including the reported fraction. Done means LaTeX math is rendered in AI answers and the CommonMark parser no longer exposes the delimiters or raw formula source.

Written by the indexing model from the issue text.