getAvailableDates(listing: Listing,holidays: Holiday[],durationOverride?: number,): string[]
A duration_days > 1 listing excludes a start date whose full range hits a
non-bookable day or runs past the booking window.
durationOverride exists for a customisable-days listing, where
duration_days is only the maximum. The date list is built for a single
day, and the chosen span is validated at submit by
isBookingRangeValid.