List NHTSA recall campaigns

Per-campaign NHTSA recall list for an employer.

Each row is one recall campaign -- campaign_number, representative make / model / component, record_date, owner_notification_date, FMVSS standard cited (if any), potentially_affected units, plus the full distinct make + model lists across the campaign as TEXT[]. Mirrors the CPSC endpoint shape (name_normalized join key, ORDER BY date DESC).