fix(plex): facet + sort refinements

- Facets now respect the watch-state filter too (In progress / Watched / Unwatched),
  so e.g. the Year bounds match the visible set (was showing the library min, not the
  filtered min).
- Genre chips sorted alphabetically (was by count).
- Sort chips ordered alphabetically by their localized label.
- Ascending/Descending chips swapped (Ascending first) and the default sort direction
  is now Ascending.
- Default sort is now Title (ascending) instead of Recently added / Descending.

frontend/src/App.tsx

@@ -251,7 +251,7 @@ export default function App() {
   const [plexScopeRaw, setPlexScope] = useAccountPersistedState(LS.plexLibrary, "both");
   const plexScope = ["movie", "show", "both"].includes(plexScopeRaw) ? plexScopeRaw : "both";
   const [plexShowFilter, setPlexShowFilter] = useAccountPersistedState(LS.plexShow, "all");
-  const [plexSort, setPlexSort] = useAccountPersistedState(LS.plexSort, "added");
+  const [plexSort, setPlexSort] = useAccountPersistedState(LS.plexSort, "title");
   const [plexPlaylistOpen, setPlexPlaylistOpen] = useState<number | null>(null); // sidebar → open a playlist
   // The expanded Plex filters live as one JSON blob (the string-only account store serializes it).
   const [plexFiltersRaw, setPlexFiltersRaw] = useAccountPersistedState(LS.plexFilters, "{}");