Cancel Payout

PAY-8 (B-007): cancel a STUCK in-flight payout (approved|disbursing → cancelled).

A payout that was approved/marked-disbursing but can never be paid (the external rail bounced, the provider rejected, the account was force-closed) was previously irrecoverable: the partial-unique one-in-flight-per-account index then made EVERY later cycle’s payout_request INSERT fail, and the generator’s blanket-except rolled back + re-failed every 10 minutes forever. Cancelling clears the in-flight slot so the account’s pipeline can advance.

Terminal: cancelled is final (status CHECK allows it). Only approved or disbursing rows can be cancelled — a paid row is real money already wired (use chargeback/correction instead) and a pending row should be rejected. Requires the disburse_payout permission (same gate as mark-disbursing / mark-paid — only a disbursement operator should void an in-flight payout). No money moves: the PAY-1 synthetic-book debit happens at mark-paid, which a cancelled payout never reaches, so there is nothing to reverse here.