Nth weekday meetups

Expand a community hall's recurring bookings, such as "every second Tuesday", into the dates that fall inside a calendar window.

Each rule is a string "label ordinal weekday interval start", for example "board 2 Tue 1 2024-01-01". A rule occurs on the ordinal-th weekday of a month: ordinal is 1 to 5 (the 2nd Tuesday, the 5th Friday, ...) or last (the last such weekday of the month). Weekdays are written Mon Tue Wed Thu Fri Sat Sun.

• The rule applies to the month containing start and then to every interval-th month after it (interval 1 is every month, 3 is every third month, and so on).
• A month that has no such occurrence (for instance a month with only four Fridays and ordinal 5) produces nothing. The occurrence is never moved to a different date.
• An occurrence earlier than start is not produced; one exactly on start is.
• Only occurrences with window_start <= date <= window_end are reported (both ends inclusive), and any occurrence on a date listed in skips is removed (for all rules).

Input: rules, a list of such strings; window_start and window_end, dates "YYYY-MM-DD"; and skips, a list of dates in the same format.

Output: a list of strings "YYYY-MM-DD label", one per remaining occurrence, ordered by date; occurrences on the same date follow the order of their rules in rules. If there are none, return [].