fix(orders): Use WooCommerce cart for shipping calculation in order creation
## Issues Fixed:
1. ✅ Shipping cost was zero in created orders
2. ✅ Live rates (UPS, Rajaongkir) not calculated
3. ✅ Shipping title shows service level (e.g., "JNE - REG")
## Root Cause:
Order creation was manually looking up static shipping cost:
```php
$shipping_cost = $method->get_option( 'cost', 0 );
```
This doesn't work for:
- Live rate methods (UPS, FedEx, Rajaongkir)
- Service-level rates (JNE REG vs YES vs OKE)
- Dynamic pricing based on weight/destination
## Solution:
Use WooCommerce cart to calculate actual shipping cost:
```php
// Initialize cart
WC()->cart->empty_cart();
WC()->cart->add_to_cart( $product_id, $qty );
// Set shipping address
WC()->customer->set_shipping_address( $address );
// Set chosen method
WC()->session->set( 'chosen_shipping_methods', [ $method_id ] );
// Calculate
WC()->cart->calculate_shipping();
WC()->cart->calculate_totals();
// Get calculated rate
$packages = WC()->shipping()->get_packages();
$rate = $packages[0]['rates'][ $method_id ];
$cost = $rate->get_cost();
$label = $rate->get_label(); // "JNE - REG (1-2 days)"
$taxes = $rate->get_taxes();
```
## Benefits:
- ✅ Live rates calculated correctly
- ✅ Service-level labels preserved
- ✅ Shipping taxes included
- ✅ Works with all shipping plugins
- ✅ Same logic as frontend preview
## Testing:
1. Create order with UPS → Shows "UPS Ground" + correct cost
2. Create order with Rajaongkir → Shows "JNE - REG" + correct cost
3. Order detail page → Shows full service name
4. Shipping cost → Matches preview calculation
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