Changing a live subscriber: re-rate and disconnect

A connected subscriber's rate can be changed without disconnecting them. Two paths do this:

• Operator plan edit (works today). Editing a plan via the REST API triggers a live re-rate: the controller walks the session table and updates the data-plane rate limiter for every connected subscriber on that plan, in place. No re-DHCP, no interruption.
• RADIUS CoA (target design). The AAA server can send a Change-of-Authorization to re-rate a subscriber, or a Disconnect-Message to drop them. The subscriber stays connected through a re-rate; a disconnect tears the session down cleanly. The CoA listener is part of the production RADIUS client.