fix(plex): an episode Plex has no number for is named by its title alone

The OS media title printed the missing number as "Enull", the player and info headers as a bare
"E". One helper for the three lines.

frontend/src/components/PlexInfo.tsx

@@ -10,6 +10,7 @@ import { DetailCustomizeMenu, Filterable, PrefToggle } from "./plexDetailUi";
 import { DetailAside, DetailAsideToggles, DetailKeywords } from "./plexDetailAside";
 import {
   DETAIL_POSTER,
+  episodeLine,
   tmdbBackdropUrl,
   useCrossfadeBackdrop,
   useDetailAside,
@@ -315,7 +316,7 @@ export default function PlexInfo({
               )}
               {detail.kind === "episode" && (
                 <p className={`text-sm ${overlay ? "text-white/70" : "text-muted"}`}>
-                  S{detail.season_number}·E{detail.episode_number} — {detail.title}
+                  {episodeLine(detail)}
                 </p>
               )}
             </div>

frontend/src/components/PlexPlayer.tsx

@@ -52,6 +52,7 @@ import { Ctrl, PanelHead } from "./plexPlayerControls";
 import { PlexPlayerSettings } from "./PlexPlayerSettings";
 import { PlexStatsOverlay } from "./PlexStatsOverlay";
 import { createFragMeter } from "../lib/plexStats";
+import { episodeLine } from "../lib/plexDetail";
 import { HlsEngine } from "../lib/hlsEngine";
 import { createHlsPort } from "../lib/hlsPort";
 import { enabled, log } from "../lib/log";
@@ -586,10 +587,7 @@ export default function PlexPlayer({ itemId, onClose, queue, fromStart = false }
   useMediaSession(
     videoEl,
     detail && {
-      title:
-        detail.kind === "episode" && detail.season_number != null
-          ? `S${detail.season_number}·E${detail.episode_number} — ${detail.title}`
-          : detail.title,
+      title: detail.kind === "episode" ? episodeLine(detail) : detail.title,
       artist:
         detail.kind === "episode" ? detail.show_title : detail.year ? String(detail.year) : null,
       artwork: api.plexImageUrl(id),
@@ -1258,9 +1256,7 @@ export default function PlexPlayer({ itemId, onClose, queue, fromStart = false }
               {detail?.kind === "episode" && detail.show_title ? detail.show_title : detail?.title}
             </div>
             {detail?.kind === "episode" && (
-              <div className="text-xs text-white/70 truncate">
-                S{detail.season_number}·E{detail.episode_number} — {detail.title}
-              </div>
+              <div className="text-xs text-white/70 truncate">{episodeLine(detail)}</div>
             )}
           </div>
           {/* Live wall clock — handy on a lean-back / HTPC screen (toggle + style in the Clock tab). */}