Cancel a running assessment

Ask a running assessment to stop. It stops within about five seconds and is finalised as cancelled, keeping the findings it had already produced, so a cancelled run is still worth reading. 202 means the request was recorded, not that the run has stopped: poll GET /api/v1/run/{run_id} until its status leaves running. Requires the same test:run scope as triggering, because stopping a run is the same authority over the same resource.

A cancelled run is not a passing run. GET /api/v1/run/{run_id} still computes a min_severity verdict once the status is terminal, and on a cancelled run that verdict covers only the categories in categories_completed -- a run stopped at minute two of twenty reads pass because it never got far enough to find anything. A pipeline that gates on the verdict alone must compare categories_completed against categories_planned, or treat cancelled as its own outcome.