Confirm the onboarding submission

Finalises the approval and pokes the queued agreement.wait.approval task so the onboarding workflow continues.

Identity verification (POST /identity) is required on both paths. In addition:

• In-app signing: POST /sign must have been called.
• Pre-signed PDF: POST /agreement must have been called.

Returns the approval flow status. A submitted status means the submission is under review; the workflow will advance once a decision is made.

{
  "status": "submitted"
}