- Add packages() relation to Shipment model
- Update CustomerOrderController to accept packages[] array
- Auto-calculate volumetric weight from dimensions (L*W*H/5000)
- Redesign order form Step 1 with Multi-Package UI
- Add package repeater (add/remove packages)
- Real-time summary of total weights
- Both real weight and dimensions are required
- Dimensions normalized to * format (5*6*9)
Phase 3.5.1 — Multi-Package complete"
