- New sync.py: reads seed import's 39-col schema, maps to main app's
customers/locations/assets schema with foreign keys
- New POST /api/sync endpoint (target=dev|prod, dry_run=true/false)
- New GET /api/sync/targets endpoint
- Category mapping: Bev→Beverage, Snack→Snack, Food→Food, etc.
- Automatically creates customers and locations from company/place
- Idempotent: updates existing assets by machine_id
- Dry-run mode: preview changes without writing
