Required roles: system-r, system-c

Update a provider ticket (async).

This endpoint returns immediately with a job_id. Use the
GET /support/provider-ticket-jobs/{job_id}/ endpoint to poll for the result.

Common field (both providers):

• client_ticket_id: Zendesk ticket ID - when provided, a comment with the update details
  will be added to the linked Zendesk ticket

Delta: Use the comment field

KPNWBA: POST /update/

• client_ticket_id: Zendesk ticket ID (required for KPNWBA API)
• additional_info: Update message

KPN WEAS: POST /messages/create/ — adds a message to the Case

• product: Product name (e.g. "WEAS")
• message_text: The message body to add
• sender_name: Optional; when omitted the provider uses
  provider_kpnweas_default_sender_name from settings

Response:

• job_id: UUID to poll for status
• status: Initial status (pending)
• message: Human-readable message
• poll_url: URL to poll for job status