Make the link underline optional

What do you want to change?

Links in rendered messages are automatically underlined.

I’d like to change that so they’re underlined only on hover (e.g., while I hold CMD key on macOS).

Why?

I'd like to visually see that I'm going to click a link and open a browser. Same experience as in iTerm / Ghostty / other terminal tools.

How? (optional)

The underline is hardcoded in packages/tui/src/components/markdown.ts: this.theme.link(this.theme.underline(linkText)). Applying the underline conditionally on a new theme token should be a small change. Happy to PR it if wanted.