feat: 属性新增fillOnPurchase字段 - 标识是否购买时填写

- ProductAttributeEntity: 新增fillOnPurchase(0:否 1:是)字段
- 区分三种属性角色: 规格属性(选择类型)/商家属性(非选择+非购买时填写)/购买时属性(fillOnPurchase=1)

src/main/java/com/cool/modules/product/entity/ProductAttributeEntity.java

@@ -26,6 +26,9 @@ public class ProductAttributeEntity extends TenantEntity<ProductAttributeEntity>
     @ColumnDefine(comment = "关联行为编码")
     private String action;
 
+    @ColumnDefine(comment = "是否购买时填写 0:否 1:是", defaultValue = "0")
+    private Integer fillOnPurchase;
+
     @ColumnDefine(comment = "状态 0:禁用 1:启用", defaultValue = "1")
     private Integer status;
 }