check availability and create a booking via ventrata's octo-compliant api

Steps

1. read docs.ventrata.com confirming Ventrata is a founding member of OCTO and implements the OCTO API Specification for resellers connecting to Ventrata-powered suppliers, with all public OCTO routes served under https://api.ventrata.com/octo
2. call POST /availability (or the optimized POST /availability/calendar for calendar rendering) to check availability; if the product's allowFreesale is not true, this step is required to obtain an availabilityId before booking
3. call POST /bookings with the productId, optionId, availabilityId, and unitItems to create a booking, which reserves availability by placing it in ON_HOLD status while payment/customer details are collected
4. call POST /bookings/{uuid}/confirm once payment is complete to finalize the booking; use POST /bookings/{uuid}/extend if you need more time before confirming, or POST /bookings/{uuid}/cancel to release the hold
5. after confirmation, read booking.supplierReference, booking.voucher or booking.unitItems[].ticket (depending on booking.deliveryMethods), and booking.pricing.retail/net from the response for guest delivery and reconciliation
6. use GET /bookings or GET /bookings/{uuid} with one primary filter (e.g. resellerReference, supplierReference, localDate) to look up booking status afterward