Cal.com v2 override windows control exact bookable slots

To expose hand-picked slots on an event type, give it a dedicated schedule and PATCH that schedule's overrides array with entries like {"date":"2026-10-19","startTime":"12:30","endTime":"13:00"}. A window exactly as long as the event yields one slot, and resending the array with new windows swapped out the old slots. Also PATCH the event type's bookingWindow to {"type":"range","value":[start,end]} so no dates outside the range appear. Other event types using the default schedule are unaffected.