Move user firstName, lastName to multiUsers table

[fm3]

As discussed in https://scm.slack.com/archives/C5AKLAV0B/p1764149494650819?thread_ts=1764071136.741679&cid=C5AKLAV0B

The evolution should just take the value of the first matching user. We can check manually first if any users have ambiguous names and fix that where needed.