refactor(plex): unify Plex sort onto SortControl + a single SortState (R13 S1)

Plex sort was a bespoke chip-pill row plus a separate asc/desc chip pair, with
the key in PlexState.sort and the direction hidden in PlexFilters.sortDir. Now:
- sort is one SortState {key,dir}; sortDir is dropped from PlexFilters (and from
  the facet-key destructure). The wire call still splits it into sort + sort_dir
  at the server boundary, so the backend is untouched.
- The chip sort-row is replaced by the shared SortControl (select + arrow) — the
  same idiom the feed and channel manager use. New lib/plexSort.ts owns the
  scope-dependent vocabulary (movies add duration) + the title/asc fallback.
- PlexProvider migrates the old storage in place: a legacy bare-key plexSort
  string plus the old filters.sortDir become the {key,dir} state, so an existing
  sort preference survives the upgrade.
- PlexBrowse and PlexSidebar heal the stored sort against the current scope's
  options, so a movie-only key (duration) left over after switching to shows
  can't ask the server for an unavailable sort.

Gate green: tsc clean, eslint 0 errors, prettier clean, vitest 93.

frontend/src/components/PlexBrowse.tsx

@@ -9,6 +9,8 @@ import {
   type ReactNode,
 } from "react";
 import { qk } from "../lib/queryKeys";
+import { healSort } from "../lib/columnSort";
+import { plexSortOptions, PLEX_SORT_FALLBACK } from "../lib/plexSort";
 import { createPortal } from "react-dom";
 import { useTranslation } from "react-i18next";
 import {
@@ -90,6 +92,13 @@ export default function PlexBrowse() {
   const { q, scope, show, sort, filters, playlistOpen: openPlaylist } = usePlex();
   const { setScope, setFilters, setPlaylistOpen } = usePlexActions();
   const dq = useDebounced(q.trim(), 350);
+  // 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 = healSort(
+    sort,
+    plexSortOptions(scope, () => ""),
+    PLEX_SORT_FALLBACK,
+  );
   const sub = useHistorySubview<Sub>({ kind: "grid" });
 
   // Sidebar asked to open a playlist → push it as a subview (browser Back returns to the grid), then
@@ -141,14 +150,14 @@ export default function PlexBrowse() {
   }, [sub]);
 
   const browseQ = useInfiniteQuery({
-    queryKey: qk.plexLibrary(scope, dq, sort, show, filters),
+    queryKey: qk.plexLibrary(scope, dq, sortState, show, filters),
     enabled: !!scope && sub.view.kind === "grid",
     initialPageParam: 0,
     queryFn: ({ pageParam }) =>
       api.plexLibrary({
         scope,
         q: dq || undefined,
-        sort,
+        sort: sortState,
         show,
         filters,
         offset: pageParam as number,

frontend/src/components/PlexProvider.tsx

@@ -1,5 +1,7 @@
 import { createContext, useCallback, useContext, useMemo, useState, type ReactNode } from "react";
 import { EMPTY_PLEX_FILTERS, type PlexFilters } from "../lib/api";
+import { parseSortState, type SortState } from "../lib/columnSort";
+import { PLEX_SORT_FALLBACK } from "../lib/plexSort";
 import { getAccountRaw, LS, setAccountRaw } from "../lib/storage";
 
 // Owns the Plex module's shared local state — the left-rail library scope / watch-state / sort /
@@ -17,7 +19,7 @@ import { getAccountRaw, LS, setAccountRaw } from "../lib/storage";
 type PlexState = {
   scope: string; // movie | show | both (unified cross-library scope)
   show: string;
-  sort: string;
+  sort: SortState; // {key,dir}; healed against the scope's options at the point of use
   filters: PlexFilters;
   q: string;
   playlistOpen: number | null;
@@ -26,7 +28,7 @@ type PlexState = {
 interface PlexActions {
   setScope: (v: string) => void;
   setShow: (v: string) => void;
-  setSort: (v: string) => void;
+  setSort: (v: SortState) => void;
   setFilters: (f: PlexFilters) => void;
   setQ: (q: string) => void;
   setPlaylistOpen: (id: number | null) => void;
@@ -35,7 +37,7 @@ interface PlexActions {
 const StateContext = createContext<PlexState>({
   scope: "both",
   show: "all",
-  sort: "title",
+  sort: PLEX_SORT_FALLBACK,
   filters: EMPTY_PLEX_FILTERS,
   q: "",
   playlistOpen: null,
@@ -64,7 +66,30 @@ export function PlexProvider({ children }: { children: ReactNode }) {
     return ["movie", "show", "both"].includes(v) ? v : "both";
   });
   const [show, setShowState] = useState<string>(() => getAccountRaw(LS.plexShow) ?? "all");
-  const [sort, setSortState] = useState<string>(() => getAccountRaw(LS.plexSort) ?? "title");
+  // Sort is now a {key,dir} SortState. Migrate the old shape: a legacy bare-key string in plexSort
+  // plus the direction that used to live in plexFilters.sortDir — so an existing sort preference
+  // survives the upgrade rather than snapping back to the default.
+  const [sort, setSortState] = useState<SortState>(() => {
+    const raw = getAccountRaw(LS.plexSort);
+    if (!raw) return PLEX_SORT_FALLBACK;
+    try {
+      const parsed = parseSortState(JSON.parse(raw));
+      if (parsed) return parsed;
+    } catch {
+      /* legacy bare-key string handled below */
+    }
+    let dir: "asc" | "desc" = "asc";
+    try {
+      if (
+        (JSON.parse(getAccountRaw(LS.plexFilters) ?? "{}") as { sortDir?: string }).sortDir ===
+        "desc"
+      )
+        dir = "desc";
+    } catch {
+      /* ignore */
+    }
+    return { key: raw, dir };
+  });
   // The expanded Plex filters live as one JSON blob (the string-only account store serializes it).
   const [filtersRaw, setFiltersRaw] = useState<string>(() => getAccountRaw(LS.plexFilters) ?? "{}");
   const filters = useMemo<PlexFilters>(() => {
@@ -86,9 +111,9 @@ export function PlexProvider({ children }: { children: ReactNode }) {
     setShowState(v);
     setAccountRaw(LS.plexShow, v);
   }, []);
-  const setSort = useCallback((v: string) => {
+  const setSort = useCallback((v: SortState) => {
     setSortState(v);
-    setAccountRaw(LS.plexSort, v);
+    setAccountRaw(LS.plexSort, JSON.stringify(v));
   }, []);
   const setFilters = useCallback((f: PlexFilters) => {
     const s = JSON.stringify(f);

frontend/src/components/PlexSidebar.tsx

@@ -4,11 +4,14 @@ import { useTranslation } from "react-i18next";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { Layers, ListMusic, Plus, SlidersHorizontal, X } from "lucide-react";
 import { api, EMPTY_PLEX_FILTERS, plexFilterCount, type PlexFilters } from "../lib/api";
+import { healSort } from "../lib/columnSort";
+import { plexSortOptions, PLEX_SORT_FALLBACK } from "../lib/plexSort";
 import { defaultLayout, type PanelLayout } from "../lib/panelLayout";
 import { useDebounced } from "../lib/useDebounced";
 import { useScrollFade } from "../lib/useScrollFade";
 import SidePanel from "./SidePanel";
 import PanelGroups, { type PanelItem } from "./PanelGroups";
+import SortControl from "./SortControl";
 import { usePlex, usePlexActions } from "./PlexProvider";
 
 // The Plex module's left filter column — now the shared floating SidePanel with its filter groups
@@ -24,8 +27,6 @@ type Props = {
 };
 
 const SHOW_OPTS = ["all", "unwatched", "in_progress", "watched"] as const;
-const MOVIE_SORTS = ["added", "release", "year", "rating", "duration", "title"] as const;
-const SHOW_SORTS = ["added", "release", "year", "rating", "title"] as const;
 const RATING_STEPS = [5, 6, 7, 8, 9];
 const ADDED_OPTS = ["24h", "1w", "1m", "6m", "1y"] as const;
 const DURATION_BUCKETS: { key: string; min: number | null; max: number | null }[] = [
@@ -95,7 +96,7 @@ export default function PlexSidebar({ layout, setLayout, collapsed, onToggleColl
     qc.invalidateQueries({ queryKey: qk.plexPlaylists() });
     onOpenPlaylist(pl.id);
   }
-  const { sortDir: _sd, collectionTitle: _ct, ...facetKey } = filters;
+  const { collectionTitle: _ct, ...facetKey } = filters;
   const facetsQ = useQuery({
     queryKey: qk.plexFacets(scope, show, facetKey),
     queryFn: () => api.plexFacets(scope, filters, show),
@@ -114,7 +115,7 @@ export default function PlexSidebar({ layout, setLayout, collapsed, onToggleColl
   const collections = collectionsQ.data?.collections ?? [];
 
   const fCount = plexFilterCount(filters);
-  const activeCount = fCount + (show !== "all" ? 1 : 0) + (sort !== "title" ? 1 : 0);
+  const activeCount = fCount + (show !== "all" ? 1 : 0) + (sort && sort.key !== "title" ? 1 : 0);
   const anyActive = activeCount > 0;
 
   const patch = (p: Partial<PlexFilters>) => setFilters({ ...filters, ...p });
@@ -123,12 +124,10 @@ export default function PlexSidebar({ layout, setLayout, collapsed, onToggleColl
   const clearAll = () => {
     setFilters(EMPTY_PLEX_FILTERS);
     setShow("all");
-    setSort("title");
+    setSort(PLEX_SORT_FALLBACK);
   };
 
-  const sorts = [...(scope === "movie" ? MOVIE_SORTS : SHOW_SORTS)].sort((a, b) =>
-    t(`plex.sort.${a}`).localeCompare(t(`plex.sort.${b}`)),
-  );
+  const sortOptions = plexSortOptions(scope, (k) => t(`plex.sort.${k}`));
   const durBucketKey = DURATION_BUCKETS.find(
     (b) => (filters.durationMin ?? null) === b.min && (filters.durationMax ?? null) === b.max,
   )?.key;
@@ -218,26 +217,14 @@ export default function PlexSidebar({ layout, setLayout, collapsed, onToggleColl
       id: "sort",
       title: t("plex.filter.sort"),
       body: (
-        <>
-          <ChipRow>
-            {sorts.map((s) => (
-              <Chip key={s} active={sort === s} onClick={() => setSort(s)}>
-                {t(`plex.sort.${s}`)}
-              </Chip>
-            ))}
-          </ChipRow>
-          <div className="mt-1.5 flex gap-1">
-            {(["asc", "desc"] as const).map((d) => (
-              <Chip
-                key={d}
-                active={(filters.sortDir ?? "asc") === d}
-                onClick={() => patch({ sortDir: d })}
-              >
-                {t(`plex.filter.dir.${d}`)}
-              </Chip>
-            ))}
-          </div>
-        </>
+        <SortControl
+          options={sortOptions}
+          sort={healSort(sort, sortOptions, PLEX_SORT_FALLBACK)}
+          onChange={(next) => setSort(next ?? PLEX_SORT_FALLBACK)}
+          label={t("plex.filter.sort")}
+          ascLabel={t("plex.filter.dir.asc")}
+          descLabel={t("plex.filter.dir.desc")}
+        />
       ),
     },
     ...(peopleActive