[Feature Request] Add ui.render component for welcome logo to allow mod-drawn replacements

Feature request: let mods redraw the welcome logo (Clawd).

I built a mod that draws Clawd with Hatsune Miku hair (twin tails, bows) using quadrant glyphs and the logo's own theme keys (clawd_body, clawd_background). Right now it can only live in the AbovePrompt band, because there is no ui.render component for the welcome header.

Ask: add a ui.render component for the logo, e.g. { component: 'WelcomeLogo' }, so a hook can draw its own tree in place of Clawd, or call next(e) to keep the default.

Useful props:

• surface / viewport columns
• the rows and columns the logo may take (today it is 9x3 cells; my sprite is 15x6)
• the active theme name

Nice to have: let the header grow taller when the hook's tree needs more rows, instead of clipping it.

Version: 2.1.296, terminal surface.

Environment Info

• Platform: darwin
• Terminal: xterm-256color
• Version: 2.1.296
• Feedback ID: b578aca3-ddf9-4702-b817-14ccb1298487