ticket.sx: checkout-request (events->commerce) + payment-result
(commerce->events) wire shapes — commerce imports the contract. ev/request-
ticket! holds a seat + emits a checkout request; ev/settle-payment! confirms
on :paid, releases on failure/expiry. Idempotent; late paid for a vanished
hold -> :paid-but-no-hold (refund signal). 175/175 green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
