fix(plex): player + card polish from UAT

- Player: control tooltips now open ABOVE the button (no downward viewport clip);
  keyboard use also reveals the auto-hidden controls (wake() on keydown); added a
  Download button that downloads the ORIGINAL physical file (no re-encode/repackage,
  Content-Disposition attachment via GET /stream/{rk}/file?download=1).
- Plex cards: hover affordance shows what a click does (Play / Resume / Open show)
  + a quick watched/unwatched toggle (stopPropagation, no playback) — mirrors the
  YT-feed card quick-actions. New plex i18n keys en/hu/de.
- Verified in a real browser: card hover Play overlay + watched toggle (marks watched
  without opening), player download button present, tooltip-above, keyboard reveals
  controls, correct durations (Enola Holmes 3 = 1:48:04).
- NOTE: 'The Three Diablos' showing 13:05 was NOT a bug — it is a 13-min short (file
  ffprobe = 785s); the 1h42m film is 'The Last Wish'.

backend/app/routes/plex.py

@@ -473,14 +473,22 @@ def stream_session(
 @router.get("/stream/{rating_key}/file")
 def stream_file(
     rating_key: str,
+    download: bool = False,
     user: User = Depends(current_user),
     db: Session = Depends(get_db),
 ) -> FileResponse:
-    """Serve the raw local media file with HTTP range support (direct-playable files)."""
+    """Serve the raw local media file with HTTP range support. Used both for direct-play (inline)
+    and for the player's "download original" button (`?download=1` → attachment). The download is
+    the untouched physical file — no re-encode/repackage."""
     it = _item_or_404(db, rating_key)
     src = plex_paths.local_media_path(db, it.file_path)
     if src is None:
         raise HTTPException(status_code=404, detail="Media file not found on disk")
+    if download:
+        # A clean, safe download name from the title + the real file extension.
+        ext = src.suffix or (f".{it.container}" if it.container else "")
+        base = "".join(c for c in (it.title or "video") if c.isalnum() or c in " -_.").strip() or "video"
+        return FileResponse(str(src), filename=f"{base}{ext}")
     return FileResponse(str(src))  # Starlette honours the Range header (206)