Follow-ups from the /code-review pass:
- .is-current[aria-current] now excludes aria-current="false" — the recipe is a
shared primitive and a consumer using the common `x ? "true" : "false"` idiom
would otherwise paint a non-current row as current.
- add box-shadow to the .pill/.is-current transition so the Tabs/SettingsPanel
on-state shadow fades in instead of popping (it lost the utility `transition`).
- document that .chip-solid is intentionally paint-only (composes on a site's own
geometry) so a truncating single-element chip isn't forced into inline-flex.
The 3 intentional visual changes (hover-border 55%, tag-filter transparent
resting, RemovableChip tint+border) were UAT-accepted as-is. PlexSidebar's facet
Chip (glass-card resting) deferred — wants a .pill soft-glass variant.