## Because
- The `preVerified` account-creation option existed only to cut test churn. It never worked in production.
- Tests used it, so the auth server kept a create path that no real client could reach.
## This pull request
- Removes `preVerified` from `lib/routes/account.ts`. New accounts always start unverified, and the sign-up session always gets a token verification id.
- Drops `preVerified` from the published `fxa-auth-client` surface (`lib/client.ts`), the legacy content-server client, the `test/client/api.js` helper, and the shared error constant in `libs/accounts/errors/src/constants.ts`.
- Moves account verification into the shared target helpers in `packages/functional-tests/lib/targets/`. The helpers read a real email code, so the specs stay short.
- Updates the remote tests to verify accounts with an email code.
- Updates `test/load/loadtests.py` to keep the session that `create_account` returns and to verify the signup code before the password reset and password change flows.
## Issue that this pull request solves
Closes: FXA-9550