API: I can add a key with a userid@keybase.io (packet) that doesn't match my username

This is probably ok since its ignored if not matching, but might be a good idea to add a check to make sure and userid@keybase.io user id packet (if included) in key also matches the keybase username associated with an account (if only as a sanity check).

(Yeah, I am testing wierd scenarios.)

Start by tracing the API path that accepts keys containing a userid@keybase.io packet and identify where the packet is compared with the account username. Confirm the intended behavior for mismatches, then add coverage showing that an inconsistent packet is rejected or ignored as decided. Done means the sanity check is enforced without breaking valid keys.

Written by the indexing model from the issue text.