- Add `docs/pages/ui/components/list-group.mdx` covering the base list,
flush, action items, active and disabled states, section headers,
hoverable rows with actions, transparent, numbered, horizontal, and
contextual colors.
- Add examples for a list inside a card (`card-list-group`) and a
notifications list.
- Register "List group" in `docs.json` between "Inline player" and "Modal".
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>