feat(orders): Integrate WooCommerce calculation in OrderForm
## Frontend Implementation Complete ✅
### Changes in OrderForm.tsx:
1. **Added Shipping Rate Calculation Query**
- Fetches live rates when address changes
- Passes items + shipping address to `/shipping/calculate`
- Returns service-level options (UPS Ground, Express, etc.)
- Shows loading state while calculating
2. **Added Order Preview Query**
- Calculates totals with taxes using `/orders/preview`
- Passes items, billing, shipping, method, coupons
- Returns: subtotal, shipping, tax, discounts, total
- Updates when any dependency changes
3. **Updated Shipping Method Dropdown**
- Shows dynamic rates with services and costs
- Format: "UPS Ground - RM15,000"
- Loading state: "Calculating rates..."
- Fallback to static methods if no address
4. **Updated Order Summary**
- Shows tax breakdown when available
- Format:
- Items: 1
- Subtotal: RM97,000
- Shipping: RM15,000
- Tax: RM12,320 (11%)
- Total: RM124,320
- Loading state: "Calculating..."
- Fallback to manual calculation
### Features:
- ✅ Live shipping rates (UPS, FedEx)
- ✅ Service-level options appear
- ✅ Tax calculated correctly (11% PPN)
- ✅ Coupons applied properly
- ✅ Loading states
- ✅ Graceful fallbacks
- ✅ Uses WooCommerce core calculation
### Testing:
1. Add physical product → Shipping dropdown shows services
2. Select UPS Ground → Total updates with shipping cost
3. Change address → Rates recalculate
4. Tax shows 11% of subtotal + shipping
5. Digital products → No shipping, no shipping tax
### Expected Result:
**Before:** Total: RM97,000 (no tax, no service options)
**After:** Total: RM124,320 (with 11% tax, service options visible)
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