feat(plex): up-next end-card at episode end (E6 S4)

At episode end, when a next item exists and the pref is on, show an up-next
card (poster + title + ~10s countdown + Cancel) instead of the old instant jump,
so binge stays in the viewer's control (D6-A). Countdown or Play now advances;
Cancel/✕ dismisses and stays on the finished frame. Lives only on the
play-to-the-end path — credits-auto-skip advances earlier and never reaches the
card, so the two reconcile by construction (no double-advance). New pref
'upNext' (default on) with a Playback-tab toggle; the card closes on item change
and joins the Back/Escape cascade. i18n HU/EN.

frontend/src/components/PlexPlayer.tsx

@@ -42,6 +42,7 @@ import {
 import { Ctrl, PanelHead, Skip10 } from "./plexPlayerControls";
 import { PlexPlayerSettings } from "./PlexPlayerSettings";
 import { PlexStatsOverlay } from "./PlexStatsOverlay";
+import { UpNextCard } from "./UpNextCard";
 import {
   useAutoSkip,
   useControlsVisibility,
@@ -177,6 +178,12 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
   const [statsOpen, setStatsOpen] = useState(false);
   const statsOpenRef = useRef(false);
   statsOpenRef.current = statsOpen;
+  // Up-next end-card: shown at episode end (with a next item) instead of an instant jump (S4).
+  const [upNextOpen, setUpNextOpen] = useState(false);
+  const upNextOpenRef = useRef(false);
+  upNextOpenRef.current = upNextOpen;
+  const upNextPrefRef = useRef(prefs.upNext);
+  upNextPrefRef.current = prefs.upNext;
   const now = useWallClock();
 
   durationRef.current = duration;
@@ -520,7 +527,11 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
       // (absRef 0) — its stray 'ended' must not mark anything watched or cascade another advance.
       if (absRef.current <= 0) return;
       api.plexSetState(id, "watched").catch(() => {});
-      if (nextId) go(nextId);
+      // With a next item and the up-next pref on, surface the end-card (poster + countdown + Cancel)
+      // and let IT advance — binge stays in the viewer's control (S4/D6-A). The card only appears here,
+      // on play-to-the-end; credits-auto-skip advances earlier and this handler never fires for it.
+      if (nextId && upNextPrefRef.current) setUpNextOpen(true);
+      else if (nextId) go(nextId);
       // Nothing queued next → dismiss the player back to the previous page (same as Stop/Escape),
       // instead of stranding a black, ended <video> on screen.
       else onClose();
@@ -529,6 +540,14 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
     return () => video.removeEventListener("ended", onEnded);
   }, [id, nextId, go, onClose]);
 
+  // Up-next card actions: advance = go to the next item (it was already marked watched on 'ended');
+  // cancel = dismiss and stay on the finished frame. Loading a new item closes any lingering card.
+  const advanceUpNext = useCallback(() => {
+    setUpNextOpen(false);
+    if (nextId) go(nextId);
+  }, [nextId, go]);
+  useEffect(() => setUpNextOpen(false), [id]);
+
   // "Back" cascade shared by the on-screen Back arrow AND the keyboard/remote Backspace·Escape: peel
   // off whatever is layered on top (a tuning/tracks menu, then the shortcuts sheet, then the info
   // overlay) before leaving the player. The arrow used to call onClose() unconditionally, so Back
@@ -540,6 +559,7 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
     } else if (helpOpenRef.current) setHelpOpen(false);
     else if (infoOpenRef.current) setInfoOpen(false);
     else if (statsOpenRef.current) setStatsOpen(false);
+    else if (upNextOpenRef.current) setUpNextOpen(false);
     else onClose();
   }, [onClose]);
 
@@ -651,6 +671,7 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
           } else if (helpOpenRef.current) setHelpOpen(false);
           else if (infoOpenRef.current) setInfoOpen(false);
           else if (statsOpenRef.current) setStatsOpen(false);
+          else if (upNextOpenRef.current) setUpNextOpen(false);
           else if (!fullscreenElement()) onClose();
           break;
       }
@@ -1169,6 +1190,16 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
         />
       )}
 
+      {/* Up-next end-card (episode end, next item queued, pref on). Non-modal — the finished frame
+          stays behind it; the card's own countdown advances unless the viewer cancels. */}
+      {upNextOpen && nextId && (
+        <UpNextCard
+          nextId={nextId}
+          onAdvance={advanceUpNext}
+          onCancel={() => setUpNextOpen(false)}
+        />
+      )}
+
       {/* Keyboard-shortcut cheat sheet (toggle with "h" or the keyboard button). */}
       {helpOpen && (
         <div