Moonfin-Client/Moonfin-Core ? reverse-engineered prompt

Build me a premium media app for Jellyfin and Emby that works nicely on phone, tablet, TV, desktop, and the web from one shared codebase.

I want it to feel modern and polished, with a home screen, searchable library, show and movie details, playback controls, and support for things like downloads for offline viewing, subtitles, casting, and TV remote navigation. It should also handle music, books, audiobooks, and even retro games from the server if possible, since this app is meant to be more than just a simple video player.

Please make it cross platform and keep the UI customizable, with themes, different layout styles for featured content, and a clean experience for both touch and remote control. If you need to look up current docs or best practices for Flutter and media playback, go ahead and do that.