KotatsuApp/kotatsu-syncserver — reverse-engineered prompt

Build me a simple sync server I can self host for the Kotatsu manga reader app. I want people to be able to sign up or sign in with an email and password, then use the same account on multiple devices and keep their favorites, favorite categories, and reading history synced so they can restore their library without losing anything.

Please make it easy to run on a server with Docker or Docker Compose, backed by MySQL, with settings coming from environment variables and a sample env file. I also want password reset endpoints. If mail settings are configured, send the reset email normally. If not, just print the reset message or token to the server logs. Add a simple option to allow or block new registrations after I have created my own account.

Keep the API compatible with the Kotatsu app so I can point the app to my server address and have sync start working. Include clear startup instructions, and look up current docs online if you need to.