Fix account lookup for nicknames beginning with numbers
it looks like this is primarily a backend issue due to id to/from string parsing, not frontend, and is only still a problem because of all the pre-flake ids still around in instance databases (as in, wouldn't repro if all account ids were flake ids).
this MR is a one-line fix plus two tests.
take a look at the first-commit pipeline if you want to see the tests fail against latest develop.