ReviewCampaignExport

Phase 8: one requested campaign evidence export (async NDJSON job in review-svc). PENDING while the job streams the file; COMPLETED carries the downloadable file id (GET /api/files/:file_id) + item_count; FAILED carries the reason and no file. One export may be in flight per campaign at a time; finished exports may be repeated (each is a new record + a new file). The requester is notified (review.campaign_export_ready) when the job finishes either way.

type ReviewCampaignExport {
  completed_at: DateTimeISO
  error: String
  file_id: ID
  id: ID!
  item_count: Int
  requested_at: DateTimeISO!
  requested_by: ID!
  status: ReviewCampaignExportStatus!
}