Flutter app with server database backend and sync

Create Flutter/Dart application for registering checklists.
The app is working offline and the user can perform a sync to the server for fetching updated checklists and to return completed checklists.
The project also includes the server backend.
The server database must be a sql database.
The app database can for example be firebase.
The app has to work on Android and iOs.

See attached documents for:
- description of app
- description of app database and server database
- description of sync