feat(plex): sort direction, genre any/all, multi-person filters; fix back-nav + player stop

UAT follow-ups on the Plex filter epic:
- Sort now has an asc/desc toggle (sort_dir), applied to any sort field.
- Genre multi-select gains an Any/All mode (genre_mode: OR vs AND containment).
- Director/actor/studio become multi-value: people AND (titles featuring all selected),
  studios OR; clicking them on the info page stacks (unions) instead of replacing, and
  the sidebar shows each as a removable 'Active' chip.
- fix(history): clicking a metadata filter on the info page now pushes a fresh grid
  entry instead of history.back(), so browser Back returns to the info page rather than
  leaving the Plex module.
- fix(player): fully tear down the <video> + hls on unmount and guard late play() calls,
  so backing out of a just-started video no longer leaves audio playing in the background.
i18n en/hu/de (match any/all, sort direction).

frontend/src/components/PlexPlayer.tsx

@@ -53,6 +53,9 @@ export default function PlexPlayer({ itemId, onClose }: Props) {
 
   const videoRef = useRef<HTMLVideoElement>(null);
   const hlsRef = useRef<Hls | null>(null);
+  // False once unmounted, so a late play() (from MANIFEST_PARSED / loadedmetadata firing after Back)
+  // can't start a detached <video> playing audio in the background.
+  const aliveRef = useRef(true);
   const wrapRef = useRef<HTMLDivElement>(null);
   const sessionStartRef = useRef(0); // absolute offset the current HLS/direct session begins at
   const durationRef = useRef(0);
@@ -143,7 +146,7 @@ export default function PlexPlayer({ itemId, onClose }: Props) {
         hls.on(Hls.Events.MANIFEST_PARSED, () => {
           enableSubs();
           setReady(true);
-          video.play().catch(() => {});
+          if (aliveRef.current) video.play().catch(() => {});
         });
         // A fatal HLS error (e.g. the remux session died / the file became unreadable) would
         // otherwise leave the spinner up forever — surface it instead.
@@ -157,7 +160,7 @@ export default function PlexPlayer({ itemId, onClose }: Props) {
         const onMeta = () => {
           if (sess.mode === "direct" && startAt > 0) video.currentTime = startAt;
           setReady(true);
-          video.play().catch(() => {});
+          if (aliveRef.current) video.play().catch(() => {});
           video.removeEventListener("loadedmetadata", onMeta);
         };
         video.addEventListener("loadedmetadata", onMeta);
@@ -179,6 +182,28 @@ export default function PlexPlayer({ itemId, onClose }: Props) {
     };
   }, [detail, loadSession]);
 
+  // Full media teardown on unmount (Back): stop + detach the <video> and destroy hls, so a late
+  // play() can't leave audio playing on a detached element after leaving the player.
+  useEffect(() => {
+    return () => {
+      aliveRef.current = false;
+      if (hlsRef.current) {
+        hlsRef.current.destroy();
+        hlsRef.current = null;
+      }
+      const v = videoRef.current;
+      if (v) {
+        try {
+          v.pause();
+          v.removeAttribute("src");
+          v.load();
+        } catch {
+          /* ignore */
+        }
+      }
+    };
+  }, []);
+
   // --- time tracking + progress checkpoints ----------------------------------------------------
   useEffect(() => {
     const video = videoRef.current;