Plex now shows the same at-a-glance "what's narrowing this" row the feed has,
instead of the narrowing being visible only inside the collapsed sidebar. New
usePlexActiveFilters is the Plex analogue of useActiveFilters — it turns the Plex
state (expanded filters + watch-state + sort) into the source-agnostic
ActiveFilter[] the SHARED ActiveFilterChips renders. One removable chip per
dimension (genres/ratings/people emit one each), plus Clear-all resetting filters
+ watch-state + sort. Labels reuse the existing plex.* i18n keys; no new strings.
Lives in components (not lib) since it reads the Plex provider — lib stays
provider-free like useActiveFilters. Gate green: tsc/eslint-0/prettier/knip.
Self-E2E'd: a sort=year chip renders, removing it resets sort to title and hides
the row.