v2.64.0

Add Cursor link to the site footer (#578)

## Summary
- Adds a Contentful-driven Cursor footer icon immediately left of GitHub
(`icon: "cursor"` → `BUILT_IN_ICONS`), using the official cube mark with
`currentColor` so it matches peer brand icons.
- Links Cursor to Dylan's public profile at https://cursor.com/@dyl
(verified HTTP 200 and published in Contentful entry
`3OplR5LChrkZ7tvGUCg3zn`).
- Keeps the established desktop footer layout: site metadata on the left
and icon links on the right.
- Sets icons to exactly 18px at `sm+`; mobile remains 17.5px with the
tightened 36px targets/margins.

## Test plan
- [x] `turbo check` / `check:types` / `test` for `@dg/web` + `@dg/ui`
- [x] Browser computed size: 18px at 1280, 17.5px at 390
- [x] Browser href: `https://cursor.com/@dyl`
- [x] Cursor remains immediately left of Github

# Release info

- [ ] Major
- [x] Minor
- [ ] Patch

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Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>