Disposability parity with the question provider: a gateway disposed while
approvals are pending settles every registry entry as 'cancelled' (the
service's fail-closed vocabulary), so no ctx.approval ask dangles past the
proxy's lifetime and mux subscribers see the withdrawal. Spec mounts the
proxy on its own fiber and drives dispose with a live ask.
Addresses the ds-review-bot suggestion on PR #851.
imccyu
79b1ec2eae