v0.78.1: admin idiomatic re-expression (internal)

The admin interface is re-expressed in native DaisyUI 5.6 and Tailwind 4.

The idiomatic re-expression sweep (Phases 2 through 6) retired the admin's bespoke arbitrary-token color
classes (the var(--color-muted) and var(--color-subtle) references a component wrapped in square
brackets) to the named text-muted and text-subtle role utilities across every admin component, ending
at a zero retired-token floor that a check:custom-surface gate now holds. The work changes only the
admin's internal styling, which a consumer never imports.

The public API and runtime behavior are unchanged, so an upgrading site needs no action. Phases 0 and 1 of
the same sweep (the gate and the role vocabulary, and the vocabulary-screen pilot) shipped in 0.78.0.

This release window covers v0.78.0..v0.78.1.