Report a colour utility on the application's own theme colour in the design guard

The guard knew M3's roles and Tailwind's palette, so `bg-off-plan`,
`text-sport-run`, `from-brand` or `border-l-zone-4` - colours an
application's own Tailwind theme named before 2.0.0 - were the leftovers
its count never showed, though none has compiled since. After every
other family, a class-list token shaped like a colour utility on a name
that starts with a letter is now reported with the application's own
`var(--...)` as its replacement (`color-mix()` with an opacity), unless
the application's CSS declares the class.

So that none of Tailwind's own utilities on those prefixes reads as a
theme colour, each one Tailwind 4.2 lists is now named by its family:
`border-collapse`, `border-spacing-*`, the block borders `border-bs`/
`border-be`, `bg-blend-*` and the other background positions and
angles, gradient stops, `fill-none`/`stroke-*`, `text-shadow-*`,
`shadow-inner`, `accent-auto`, `inherit`/`initial` as colour keywords,
and the `mauve`, `olive`, `mist` and `taupe` palettes; only
`inset-ring-*` is still not read. BoostVocabularyTest no longer reads
a span holding a single property, prop or role name (`border-color`,
`placeholder-value`, `outline-variant`) as a class list. A fixture
test covers the theme colours and the Tailwind names beside them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

UPGRADE.md

@@ -9,6 +9,14 @@
   it in the layout, `toggle()` opens and closes the modal rail (`show()`, `hide()`) instead of
   changing a choice nothing draws there. A shortcut that pressed the rail's menu button to get this
   can call `$store.rail.toggle()` again.
+- **`DesignGuard`** reports a colour utility on a colour the application's own Tailwind theme
+  named (`bg-brand`, `text-sport-run`, `from-brand`, `border-l-zone-4`, `bg-brand/8`) in a class
+  list, with `var(--…)` of the application's own as its replacement, unless the application's
+  CSS declares the class. None of them has compiled since 2.0.0, and they were the leftovers its
+  count never showed. Tailwind's other utilities on the same prefixes are named by their own
+  family now too: `border-collapse`, `border-spacing-*`, `from-10%`, `via-none`, `fill-none`,
+  `stroke-*`, `text-shadow-*`, `text-inherit`, and Tailwind 4.2's `mauve`, `olive`, `mist` and
+  `taupe` palettes. A test that expects no findings may fail on them.
 
 ## From 2.0.0 to 2.1.0