Fix offline behaviour

[slaweet]

Expected behaviour

There are some problems with offline indication.
When peer goes offline:

• There should be an error toast. And success toast when it goes back online
• All UI Cards should gray out and become unclickable.
• Global loading progress bar should be displayed until the connection is reestablished.

Login page should not redirect to the app and show an error toast if the peer is offline.

Actual behaviour

The only indication that the peer is offline is the red cross on Peer Card.