The video side now uses a configured Plex/Jellyfin on its own (resolve_video_
server), not config_manager.get_active_media_server(). So a music-only server
(Navidrome/SoulSync) never applies to video, and 'Navidrome for music + Plex for
video' works. Order: explicit video pick (video_server setting) → music-active if
video-capable → the single configured one → Plex if both → None. Seam tests cover
each case incl. the mixed setup.
