Check event date availability

Capture-mode note: this endpoint may return a simulated typed refusal (G1_NO_HOURLY_VENUE_INVENTORY, G2_NO_MULTI_DAY_EVENTS, G3_NO_MIDNIGHT_CROSSING, G18_ATTENDEE_CAPACITY_NOT_PRECHECKED, WINDOW_IN_PAST, ASSET_CONFLICT, DST_INSTANT_REJECTED) to exercise refusal-state handling.

The engine books whole calendar dates only — a same-evening 4-hour ask still consumes the entire date (gap G1).

Events that cross midnight are rejected outright (gap G3) — plan a same-day end time.

The engine has no multi-day event reservation — a 3-day festival must be booked as 3 separate whole-date reservations (gap G2).

Not checked against venue capacity until quote time (gap G18) — a date can look available here and still fail once priced.

Attendee counts above the space's posted certificate-of-occupancy capacity cannot be accommodated regardless of quoted price.