Keybase GUI installer can't add new device with GPG key

I have my GPG key on a Yubikey which I carry with me all the time. Consequently, the new key model doesn't really do much for me (in fact I rather dislike it since it adds another level of complexity, obscruity, and indirection to verifying proofs, but that's another issue).

With the CLI `keybase login`, I can say I don't have access to any of my other devices, then I'm given the option to add a new device with my GPG key. But this doesn't appear to be an option with the GUI installer.

Start by comparing the GUI installer flow with the CLI `keybase login` flow described in the issue, focusing on recovery when no other devices are available. Confirm where the GUI handles device enrollment and GPG-key authentication. Done means the GUI offers a working option to add a new device with a GPG key in that situation.

Written by the indexing model from the issue text.