Phase 1: Receive/Display on RG

• Extend the Pi broker to expose stable, trimmed rating/social metadata from Jellyfin plugin data or Jellyfin item fields.
• Keep payloads small and safe for RG.
• Display on the existing media detail panel:
  • Letterboxd/Jellyfin user rating
  • community average and count where available
  • watchlist/favorite status
  • short review excerpt if available
• Avoid client-side direct Letterboxd access from RG.