Calendar links now book on non-product pages

Booking calendars opened from a calendar link now book correctly on pages that are not product pages. Before this fix, some shoppers got a generic error when they tried to book. If the event has more than one variant and the link does not pick one, shoppers now see a clear message instead. Booking errors, such as a rate limit or a server problem, now appear in a dialog that uses your selected day color instead of a browser alert.