Use interview_state from the api.hirevoice.ai webhook as the only source of
truth for interview outcome. Ignore other fields for outcome decisions,
including status, is_call_successful, is_over_3min_call, and
duration_seconds. They are informational only.
All webhooks are HTTP POST requests with a JSON body. Requirements:
- Accept
Content-Type: application/json. - Return a 2xx status code to acknowledge receipt.