ON CONFLICT (id) DO NOTHING only catches the id itself, so every other
failure (duplicate username/phone/signup_email) was reported as a generic
"already exists (or insert failed)" - not useful for telling apart the four
distinct causes.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
auth.signUp never lets a caller pick a user id (users_id_seq always
assigns it), but users.id is GENERATED BY DEFAULT rather than ALWAYS, so
an explicit id in the INSERT is honored - the same mechanism
ensureOfficialSystemUserWithDB already relies on to seed the built-in
system accounts at fixed ids.
createuser -id N [-phone ...|-email ...] inserts a user row at that id
for local/dev use, refusing (unless -force) a reserved system-account id
or one at/above UserIDSequenceBase where a future organic signup could
collide with it. -email reproduces the real email-signup path exactly:
a synthetic 888-prefixed display phone (domain.NewEmailSignupDisplayPhone,
re-rolled on collision) plus the real address in signup_email, rather
than storing the address in users.phone directly.
