v0.89.0: the admin toolkit — a public subpath, and cairn's admin re-expressed on it

The admin-toolkit organization pass: a new public subpath, and cairn's own admin re-expressed on it.

Added

• A new public subpath, @glw907/cairn-cms/admin-toolkit, packages the general-purpose admin
  components and formatters a consumer site's own admin build proved first: PageHeader,
  ListToolbar, AdminTable, StatusChip, Pagination, EmptyState, and the
  formatMoney/formatCivilDate/formatTimestamp/ageFromBirthdate formatters. A site building
  its own /admin/ screen reaches for the same shared vocabulary cairn's own admin now uses,
  instead of hand-rolling a bespoke parallel. See the admin-toolkit reference page
  (docs/reference/admin-toolkit.md).

Changed

• cairn's own admin screens now build on that toolkit. ConceptList, CairnMediaLibrary,
  ManageEditors, VocabularyAdmin, CairnTidySettings, NavTree, and HelpHome all render
  their page header through the toolkit's PageHeader, converging five ad hoc header markups
  into one visible idiom: an optional eyebrow, the display-face title, an optional muted meta
  line, and one right-aligned action. ConceptList and CairnMediaLibrary also converge their
  search, filter, count, table, and pager markup onto ListToolbar, AdminTable, StatusChip,
  and Pagination. A site that already matched the old per-screen headers and lists by eye may
  notice the rhythm settle to one shape; no prop or route contract changed.

Fixed

• The admin CSS build's @source scan never included src/lib/admin-toolkit, so any daisyUI or
  Tailwind class used only there silently never compiled. A new CI gate,
  check:admin-css-classes, checks every admin component template's class tokens against the
  built sheet so a class miss like this fails CI instead of shipping.

No consumer action is required. The new subpath is additive, and the visible header convergence
touches only cairn's built-in admin screens, with no exported contract behind it.