[FR]: Add login functionality to the app

Is there an existing issue for this?

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Describe the problem

A typical app should deal with login, including say authenticated requests. It would be good to have a nice sample for this. Not sure exactly what should be implemented by ideas

a) Server with oauth support b) Integration with Google Signin c) Some persistence associated with accounts

If we eventually add a Wear app here, it would be good to show some good examples for login with paired and standalone devices also.

Describe the solution

Implement accounts and login in the app and server.

Additional context

No response

Code of Conduct

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@yschimke so this is planned, along with multiple user accounts all backed by google sign in. We just need a few integration pieces to fall in before we can implement it.