feat: 수주 목록/상세 필드 개선

- OrderService: client relation에 manager_name 추가
- Order 모델: shipping_cost_label accessor 추가 (common_codes 조회)
- $appends에 shipping_cost_label 추가

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Models/Orders/Order.php

@@ -149,6 +149,7 @@ class Order extends Model
      */
     protected $appends = [
         'delivery_method_label',
+        'shipping_cost_label',
     ];
 
     /**
@@ -255,6 +256,16 @@ public function getDeliveryMethodLabelAttribute(): string
         return CommonCode::getLabel('delivery_method', $this->delivery_method_code);
     }
 
+    /**
+     * 운임비용 라벨 (common_codes 테이블에서 조회)
+     */
+    public function getShippingCostLabelAttribute(): string
+    {
+        $shippingCostCode = $this->options['shipping_cost_code'] ?? null;
+
+        return $shippingCostCode ? CommonCode::getLabel('shipping_cost', $shippingCostCode) : '';
+    }
+
     /**
      * 수주확정 시 매출 생성 여부
      */