Spec 12 S1: migration 0012 (password_hash nullable, user_identities, sessions.method and the
OpenID token columns), auth.mode (only "password" until S2), GET /api/auth/methods, login body
{login, password} (email still accepted), signIn on users and /api/auth/me, a Signs in with
column on Users. The last active admin with a password can't be deleted, disabled or demoted.