Required roles: broadband-r

Returns the RADIUS post-auth log for the connection's circuits, newest first.

Cursor pagination: when results are full at limit, pagination.next carries a URL whose
before cursor is the timestamp of the oldest entry in the current page.
after is intended for polling — it filters to entries strictly newer than the given cursor;
the next-page link still uses before so the caller can keep paging back through history
independently of the polling cursor.