Upsert the reservation for the itinerary. Call this AFTER the Stripe payment has been confirmed on the frontend. The response contains the human-readable reservation code shown on the thank-you page.
Use Authorization: Bearer <access_token> from POST /v1/oauth/token, or Authorization: Bearer <api_key>. Dev-only example key (do not use in production): see repository README.
Distribution channel brand: matches channel name or domainUrl (e.g. Weebora, weebora.com, booking.hofj.com, terrarossa.com). The resolved domain is BOTH the upstream host AND the tenant routing value. If omitted, CONTENT_DEFAULT_CHANNEL_DOMAIN must be set server-side.
Locale for the brand site (it, en, es, fr). Injected as /{locale}/api/... on the upstream call. Defaults to CONTENT_DEFAULT_LOCALE.
it, en, es, fr Itinerary to confirm.