chore(plex): drop dead _enabled guard, dedup watch-toggle, remove dead i18n

- plex.py: delete the no-op _enabled() (never wired as a Depends/called; the real
  gate is sysconfig plex_enabled).
- PlexBrowse.tsx: collapse toggleEpisodeWatched into toggleWatched — they were
  byte-identical (both take a PlexCard).
- Delete 6 dead plex.json keys (loadMore, playerSoon, filter.library,
  playlist.up/down/remove) from en/hu/de — verified 0 refs (the live
  playlist.removeShow/removeSeason keys are kept).

Behavior-neutral. tsc green, ruff clean on touched files, localdev boots, Plex renders.

frontend/src/components/PlexBrowse.tsx

@@ -211,12 +211,6 @@ export default function PlexBrowse({
     await api.plexSetState(card.id, next).catch(() => {});
     qc.invalidateQueries({ queryKey: ["plex-library"] });
   }
-  async function toggleEpisodeWatched(ep: PlexCard) {
-    const next = ep.status === "watched" ? "new" : "watched";
-    optimisticStatus(ep.id, next);
-    await api.plexSetState(ep.id, next).catch(() => {});
-    qc.invalidateQueries({ queryKey: ["plex-library"] });
-  }
   // Apply a metadata filter (clicked on an info page / show hero / cast) then show the unified grid.
   // Array filters (genres/people/studios) UNION with what's set; scalars replace. Clicking a person
   // (cast/crew) widens to the 'both' scope so their movies AND shows show up together (mixed feed).
@@ -348,7 +342,7 @@ export default function PlexBrowse({
                     ep={ep}
                     withShowTitle
                     onPlay={() => onCard(ep)}
-                    onToggleWatched={() => toggleEpisodeWatched(ep)}
+                    onToggleWatched={() => toggleWatched(ep)}
                   />
                 ))}
               </div>

frontend/src/i18n/locales/de/plex.json

@@ -12,7 +12,6 @@
     "release": "Erscheinungsdatum"
   },
   "filter": {
-    "library": "Bibliothek",
     "scope": "Bibliothek",
     "scopeOpt": {
       "both": "Alle",
@@ -67,7 +66,6 @@
   "noMatchesFiltered_other": "Keine Treffer — {{count}} Filter schränken die Ergebnisse zusätzlich ein.",
   "loading": "Wird geladen…",
   "empty": "Noch nichts hier. Starte eine Plex-Synchronisierung auf der Admin-Konfigurationsseite.",
-  "loadMore": "Mehr laden",
   "watched": "Angesehen",
   "inProgress": "Läuft",
   "play": "Abspielen",
@@ -92,7 +90,6 @@
     "markSeasonUnwatched": "Staffel als ungesehen",
     "addShowCollection": "Zur Sammlung"
   },
-  "playerSoon": "Player kommt bald — „{{title}}“",
   "collEditor": {
     "manage": "Sammlungen",
     "title": "Sammlungen — {{title}}",
@@ -218,9 +215,6 @@
     "playAll": "Alle abspielen",
     "delete": "Playlist löschen",
     "empty": "Diese Playlist ist leer. Füge Titel über deren Infoseite hinzu.",
-    "up": "Nach oben",
-    "down": "Nach unten",
-    "remove": "Entfernen",
     "layoutAccordion": "Akkordeon-Ansicht",
     "layoutTree": "Baum-Ansicht",
     "removeShow": "Ganze Serie entfernen",

frontend/src/i18n/locales/en/plex.json

@@ -12,7 +12,6 @@
     "release": "Release date"
   },
   "filter": {
-    "library": "Library",
     "scope": "Library",
     "scopeOpt": {
       "both": "All",
@@ -67,7 +66,6 @@
   "noMatchesFiltered_other": "No matches — {{count}} filters are also narrowing the results.",
   "loading": "Loading…",
   "empty": "Nothing here yet. Run a Plex sync from the admin Config page.",
-  "loadMore": "Load more",
   "watched": "Watched",
   "inProgress": "In progress",
   "play": "Play",
@@ -92,7 +90,6 @@
     "markSeasonUnwatched": "Mark season unwatched",
     "addShowCollection": "Add to collection"
   },
-  "playerSoon": "Player coming soon — “{{title}}”",
   "collEditor": {
     "manage": "Collections",
     "title": "Collections — {{title}}",
@@ -218,9 +215,6 @@
     "playAll": "Play all",
     "delete": "Delete playlist",
     "empty": "This playlist is empty. Add titles from their info page.",
-    "up": "Move up",
-    "down": "Move down",
-    "remove": "Remove",
     "layoutAccordion": "Accordion view",
     "layoutTree": "Tree view",
     "removeShow": "Remove whole show",

frontend/src/i18n/locales/hu/plex.json

@@ -12,7 +12,6 @@
     "release": "Megjelenés dátuma"
   },
   "filter": {
-    "library": "Könyvtár",
     "scope": "Könyvtár",
     "scopeOpt": {
       "both": "Mind",
@@ -67,7 +66,6 @@
   "noMatchesFiltered_other": "Nincs találat — {{count}} szűrő is szűkíti az eredményt.",
   "loading": "Betöltés…",
   "empty": "Még nincs itt semmi. Futtass egy Plex-szinkront az admin Konfiguráció oldalról.",
-  "loadMore": "Több betöltése",
   "watched": "Megnézve",
   "inProgress": "Folyamatban",
   "play": "Lejátszás",
@@ -92,7 +90,6 @@
     "markSeasonUnwatched": "Évad jelölés visszavonása",
     "addShowCollection": "Kollekcióhoz adás"
   },
-  "playerSoon": "A lejátszó hamarosan jön — „{{title}}”",
   "collEditor": {
     "manage": "Kollekciók",
     "title": "Kollekciók — {{title}}",
@@ -218,9 +215,6 @@
     "playAll": "Összes lejátszása",
     "delete": "Lista törlése",
     "empty": "Ez a lista üres. Adj hozzá címeket az info-oldalukról.",
-    "up": "Fel",
-    "down": "Le",
-    "remove": "Eltávolítás",
     "layoutAccordion": "Harmonika nézet",
     "layoutTree": "Fa nézet",
     "removeShow": "Egész sorozat eltávolítása",