Support markdown renderer in feed so mods can output formatted into

Summary

Am building a mod that renders schema db files and also displays table info.

I'd like to have the mod use a ui render that output markdown and the feed rendered it as such.

But any markdown generated is un-formatted:

I'm told that:

⠶ The mod feed surface doesn't support markdown rendering — it's strictly line-based with ANSI escape codes. From the docs: "Rendering is deliberately line-based,
  not component-based." There's no way to render a markdown pipe table in the feed from a mod command. The compact per-column format with colored badges is the
  best that's possible on this surface.

There is a custom renderer so it can output ANSI like:

But markdown could be nice or even larger reddened like Mermaid markdown for graphs and diagrams.

Expected Behavior

Markdown to look render markdown in feed

Actual Behavior

Just raw text

Steps to reproduce the issue

• Build a mod that outputs markdown

Command Code Version

1.5.0

Operating System

macOS

Terminal/IDE

ghostty

Shell

zsh

Additional context

No response

从 feed 界面的基于行的渲染文档开始，并使用会输出 markdown 的 mod 重现该问题。确定预期支持的 markdown 范围，以及它应如何与 ANSI 输出共存；完成的标准是 mod 输出的 markdown 在 feed 中被渲染，而不是显示为原始文本。