Mastodon social proofs requires a minimum of 2 characters

Mastodon supports single character usernames, which are super cool. Unfortunately, Keybase insists I write atleast two characters.

That's why I can't verify http://mastodon.technology/@g

Reproduce the Mastodon verification failure with the single-character username in the linked Mastodon URL and inspect the social-proof validation path. Confirm that a one-character handle can be accepted without weakening other username checks; done means the verification succeeds for @g and existing multi-character cases still work.

Written by the indexing model from the issue text.