Cancel a lease before it goes ACTIVE (REQUESTED or CONFIRMED). Renter: you changed your mind. Host: decline a confirmed booking on your body. Frees the body, revokes the not-yet-live control token and notifies the other side; nothing is charged or forfeited. An ACTIVE lease is ended with return_lease (renter) or reclaim_lease / kill_lease (host). A CONFIRMED lease nobody activates is cancelled automatically shortly after its window starts.