ad-repo/nullplayer ? reverse-engineered prompt

Build me a macOS music player called NullPlayer that feels like a throwback Winamp style app, but with a modern polished look too. I want it to play my local music and also connect to Plex, Jellyfin, Emby, Navidrome, Subsonic, internet radio, and YouTube downloads. It should handle common audio and video formats, support gapless playback, crossfade, EQ, sleep timer, and show album art and visualizers.

I also want casting to AirPlay, Chromecast, Sonos, and DLNA, plus a menu bar compact mode and a headless command line mode for automation. Make the interface switchable between Classic, Modern, and Metal styles without restarting, and keep playback going while the windows change. If you need to look up current docs online for any of the integrations, go ahead.