📄️Booking window rules in force today
Readable by every signed-in user. city_id null is the general rule; a city's own row wins over it, even one with a null last_bookable_date (no limit). A city with no row follows the general rule, and with no general row there is no limit. The rule that applies to a family is the one of its billing city. With student_id the answer also carries `resolved`, the limit for that student: a family may ask about its own students, a teacher about those they have a lesson with (cancelled lessons do not count), an admin about any; any other id is a 404.