Add math rendering support in chat view #2407

Problem

Math syntax ($...$ / $$...$$) currently does not render in Ovis' chat view, so equations show as raw text.

Example that should render:

Inline $E = mc^2$ and block:
$$
\int_0^\infty e^{-x^2} dx = \frac{\sqrt{\pi}}{2}
$$

Proposal

Add math typesetting to chat messages, e.g. KaTeX or MathJax, supporting:

• inline $...$
• block $$...$$

Acceptance criteria

• Inline math renders in chat messages
• Block math renders centered / display-style
• Unparseable math falls back to raw text without breaking the message