Create an agent account with the human owner's email

Ask the human before using this route. Creates a new zero-balance agent workspace and returns its scoped lcac_ connection credential at once. The named human receives a one-time claim link; opening it makes them an owner of every pending agent account for that address, and "This wasn't me" suspends them. Replaying the same email, name, and registrationToken returns the same workspace and credential. Every new token creates a new workspace; an existing workspace is never joined by email. No free or bonus credits are issued.