contentauth/c2pa-android ? reverse-engineered prompt

Build me an Android library that lets an app read, validate, create, and sign C2PA content, with a simple Kotlin API on top of native code.

I want it to work as an AAR that can be dropped into an Android project, and I want a small example app plus a test app so I can see it working end to end. It should support reading manifests from files or streams, signing content, and using different signing options like direct signing, a callback based signer, a web service signer, and Android Keystore or StrongBox when available.

Please also include a lightweight signing server for development and testing remote signing flows, and make sure the library is set up to run on Android 9 and up. If you need to check current Android or C2PA docs while building it, look them up online.