feature request: searching for "known" users to add to a new chat

Just an idea I had today while searching for a keybase user with a very common name in their username to add to a new chat. I typed in their first name and was returned with all of the people with that text in their username, including people I don't know/follow on keybase. It would be nice if there was a way to either search only through users I "know" (e.g. have chatted with) or users I am following. Alternatively, it might be nice to be able to prefer/sort those users at the top of the list returned when searching to keep the user from having to scroll through the list looking for the right user.

Start by reviewing the new-chat user search flow described in the issue, including how results are currently selected and ordered. Clarify whether the desired outcome is filtering to known or followed users, preferring those users, or both; done should be defined by an agreed search behavior and corresponding validation.

Written by the indexing model from the issue text.