rive-app/rive-flutter ? reverse-engineered prompt

Build me a Flutter package that lets apps play Rive animations and control them at runtime.

I want it to load .riv files from assets and let me use them in Flutter apps and games, with support for playing artboards, switching animations, handling state machines, and working with data binding and asset loading. It should let me choose whether to use Rive’s renderer or Flutter’s renderer when creating the file, and it should work on iOS, Android, macOS, Windows, Linux, and web.

Please include a simple example app that shows how to load a Rive file, render it on screen, and interact with it. Make sure the setup is smooth, with clear instructions for getting the native pieces needed for local development and testing. If anything depends on current Flutter behavior or renderer quirks, check the latest docs online and make the example reliable.