Problem Definition

When running in docker, the lifecycle of the frontend is not directly tied to that of the the backend, like the electron app.

This means that the backend can continue having a logged user while the frontend closes or gets opened from another browser.

If this happens on the same browser window, or if all the other windows are closed #3155 should improve the user experience a bit. However, there are some edge cases remaining.

One example of such a case, is when a user has a browser window open somewhere and attempts to log in with the same or another user on a different location.

With the current implementation, the other frontend will get also keep polling and reading messages (after a temporary error in the case of a different user) which might affect the functionality of the active session, since the backend is not designed for multiple frontends running at the same time.

A solution is needed where any other sessions are automatically terminated and any connected frontend goes back to the login screen when a new session starts in a new browser window.