Milestones and due dates on cards

Cards now carry two things that previously required opening the issue to find out: the milestone it belongs to and the date it is due.

The milestone renders as a pill and the due date as a chip, with the chip reflecting how close the date is, so an overdue card looks overdue at a glance rather than after arithmetic.

Both are mapped on GitLab and GitHub. GitHub calls the due date something different on its side, which is our problem rather than yours.

Both fields are also on the v1 API's issue payload, so anything you have built against it can see them too.