List a fulfillment order's tracking events (chronological timeline)

Returns every tracking event of the fulfillment order ordered by occurred_at ascending — the full timeline, not paginated. Read-only: events are written on each fulfillment order status transition and on cancellation. Each event carries the status change (previous_status -> new_status), the actor (user or service account) and any metadata (e.g. a cancellation reason). Validates that the parent fulfillment order exists. accountCode comes from the JWT.