Fix AP outbox pagination
This fixes the ActivityPub /outbox
endpoint pagination.
Since outboxes are sorted chronologically descending (newest first), the max id will be found at the top of the list, instead of at the bottom, so the next page link should have the max_id
of whatever the last (in the list) post on the previous page was.
Note that there is also an issue with the id
field which I haven't attempted to tackle: requests with max_id
do not include the max_id
activity, so if you follow the id
link you'll actually go to a different page.