Dogfood finding #3: upsertPerson resolved existing records by id only.
The wizard upserts a bootstrap admin AFTER a provider sync has already
created a person for the same Tailscale user (no id passed), so the same
providerUserId was duplicated into two records. Resolve existing by
providerUserId when no id is given; bootstrap Admin group + protectedAt are
preserved on the merge. New regression test; full suite 3414/3414.
Hermes Agent