Proper feedback when scanning QR code or opening a deeplink

As a user, when I scan a QR code or open a deeplink on another network, then either make it work on the selected network, OR throw an error it if the link doesn't work on this network.

Start by locating the QR-code and deeplink handling entry points in the mobile app and trace how the selected network is checked. Reproduce the cross-network case described in the issue; done means the link either works on the selected network or presents an error when it cannot.

Written by the indexing model from the issue text.