feat(plex): active-filter chip row above the grid (R13 S2)

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.

frontend/src/components/PlexBrowse.tsx

@@ -9,7 +9,7 @@ import {
   type ReactNode,
 } from "react";
 import { qk } from "../lib/queryKeys";
-import { healPlexSort } from "../lib/plexSort";
+import { healPlexSort, PLEX_SORT_FALLBACK } from "../lib/plexSort";
 import { createPortal } from "react-dom";
 import { useTranslation } from "react-i18next";
 import {
@@ -59,6 +59,8 @@ import PlexPlaylistAdd, { type PlexAddTarget } from "./PlexPlaylistAdd";
 import PlexCollectionEditor from "./PlexCollectionEditor";
 import { LoadingState, StateMessage } from "./QueryState";
 import { PageToolbar } from "./PageShell";
+import ActiveFilterChips from "./ActiveFilterChips";
+import { usePlexActiveFilters } from "./usePlexActiveFilters";
 import { usePlex, usePlexActions } from "./PlexProvider";
 
 // Lazy: the rich player (pulls in hls.js) loads only when something is first played.
@@ -89,8 +91,16 @@ export default function PlexBrowse() {
   // search term (q) comes from the shared header box; the rail hands off a playlist to open via the
   // shared `playlistOpen` slot, which we consume into a history subview then clear.
   const { q, scope, show, sort, filters, playlistOpen: openPlaylist } = usePlex();
-  const { setScope, setFilters, setPlaylistOpen } = usePlexActions();
+  const { setScope, setShow, setSort, setFilters, setPlaylistOpen } = usePlexActions();
   const dq = useDebounced(q.trim(), 350);
+  // Plex's active-filter chip row (above the grid), the shared feed idiom: one removable chip per
+  // narrowing, plus a Clear-all that resets filters + watch-state + sort to their defaults.
+  const plexChips = usePlexActiveFilters();
+  const clearAllFilters = () => {
+    setFilters(EMPTY_PLEX_FILTERS);
+    setShow("all");
+    setSort(PLEX_SORT_FALLBACK);
+  };
   // The provider holds sort scope-agnostically; heal it against THIS scope's options so a movie-only
   // key (e.g. duration) left over from before a switch to shows doesn't ask for an unavailable sort.
   const sortState = healPlexSort(sort, scope);
@@ -333,6 +343,8 @@ export default function PlexBrowse() {
         </div>
       </PageToolbar>
 
+      <ActiveFilterChips filters={plexChips} onClearAll={clearAllFilters} />
+
       {personCards.length > 0 && (
         <div className="mb-4 flex flex-wrap gap-3">
           {personCards.map((p) => (