Rebuild /about around an identity hero: instance branding with custom
profile fallbacks, a demo badge, and version/commit chips linked to the
GitHub release and commit. Dev builds show a plain version chip and hide
the unknown-commit chip.
Project links become an annotated directory (homepage, docs, API docs,
GitHub repo), followed by an MIT license note. The bird sprite gallery
moves out of the page, and the version/commit block leaves the settings
sidebar now that /about owns build info.
Mirror the #tag mark so the TipTap editor styles @username while typing
and on load, matching the read-only view. A shared mention grammar
(utils/mention-grammar.ts) feeds both the editor tokenizer and the
read-only remark renderer so they can't drift.
Styling only -- no autocomplete dropdown (ListUsers is admin-only and
there is no user-search RPC). Bare emails still autolink to mailto: and
are never treated as mentions: the tokenizer's start() skips email-glued
@s so marked's GFM autolinker keeps seeing the whole address.
