Appointment booking date picker should respect availability

Is your feature request related to a problem? Please describe.

As a user I typically configure my appointments Mo-Fr at my working hours, or even more restricted. When someone opens the booking page they are only able to pick dates in the future and past the minimum time before the next slot. However, days that are not available in general are also selectable. The more restrictive my availability, the more prominent that problem becomes. E.g. if I only put my appointment as available on a Wednesday, Thu-Tue "look" available to the booking person.

Describe the solution you'd like

Disable fully unavailable days from the booking date picker.

Describe alternatives you've considered

N/a

Additional context

We have to factor in time zones for this. E.g. first determine what day of the week the local time stamp will be for the organizer, then translated this into day for the booking person and exclude those days.

Start at the appointment booking page and its date picker, then trace how organizer availability and booking-person time zones are evaluated. Confirm the change by checking that fully unavailable weekdays cannot be selected while valid days remain selectable.