REST-conventional path-param variant of POST /conversation/cancel.

Behavior differs from the body form. This path-param endpoint only cancels calls that are still in the IN_QUEUE state — calls that have already started dialing or are in progress return 400 Bad Request with errors: ["Conversation with ID ... is not in queue and cannot be cancelled"]. Use the body form (POST /conversation/cancel) if you need to cancel an in-progress call.

The path param is the callId string (e.g. CALL-1778226705739-7e4c17), not the Mongo _id. Passing _id returns 404 No conversation found.

{
  "status": true,
  "data": {
    "status": "cancelled"
  }
}