refactor(vo): 重构VO对象结构，统一字段命名和接口实现

重构所有VO对象，统一字段命名规范，移除冗余字段，优化接口实现
新增Voable接口用于VO对象转换
调整BaseViewModel和ProjectBasedViewModel接口定义
更新相关服务和控制器以适应VO对象变更

common/src/main/java/com/ecep/contract/vo/PurchaseOrderItemVo.java

@@ -1,22 +1,28 @@
 package com.ecep.contract.vo;
 
+import java.time.LocalDate;
+
 import com.ecep.contract.model.IdentityEntity;
+
 import lombok.Data;
 
 @Data
 public class PurchaseOrderItemVo implements IdentityEntity {
     private Integer id;
+
+    private Integer order;
+    private Integer inventoryId;
+
     private Integer purchaseOrderId;
     private Integer contractItemId;
-    private Integer inventoryId;
     private String itemName;
-    private Integer unitId;
+    private Integer refId;
     private Double quantity;
-    private Double unitPrice;
-    private Double totalPrice;
+    private Double price;
     private Double taxRate;
-    private Double taxAmount;
-    private Double totalAmount;
-    private Integer order;
+    private Double exclusiveTaxPrice;
+
     private String remark;
+    private LocalDate arriveDate;
+    private String description;
 }