Assistant panel: <ins> and <u> HTML elements not rendered with underline styling

[aeterno-caspian]

Body

Inline HTML elements <ins> and <u> are not rendered with underline text decoration in the Assistant panel's markdown output. The tags are either stripped or rendered as plain unstyled text.

Steps to reproduce

1. Open the Assistant panel
2. Ask the model to output <ins>underlined text</ins> or <u>underlined text</u>
3. Observe that no underline styling appears

Expected behavior

Text wrapped in <ins> or <u> tags should render with underline text decoration, consistent with how these elements render in standard markdown processors that support inline HTML (GitHub, VSCode markdown preview, Obsidian, etc.).

Context

<ins> is a standard HTML inline element used for indicating inserted text, and its default browser styling is text-decoration: underline. Several markdown specifications (CommonMark, GFM) pass through inline HTML for rendering. Supporting this element would enable models to provide visual emphasis through underline as a distinct channel from bold and italic.