google/ExoPlayer ? reverse-engineered prompt

Build me a working Android media player project based on this repository so I can play local and streaming video and audio in a simple demo app.

I want the library and demo to compile cleanly, run on a modern Android Studio setup, and include basic playback controls like play, pause, seek, and fullscreen. If anything in this repo is outdated, please use the current AndroidX Media3 guidance and the migration script, since this project is deprecated and the old ExoPlayer code is no longer being updated. Keep the demo simple and practical, with a clear example of how to hook up a media item, show playback state, and handle errors gracefully.

If you need to check current docs online, do that. Also make sure the project is easy to run from scratch, with any setup steps clearly handled in the code or README.