feat: 添加VendorGroupRequireFileTypeVo及相关服务功能

refactor: 重构多个服务类和方法，优化代码结构
fix: 修复PermissionVo中code字段更名为key的问题
docs: 更新create_vo.md文档，添加新创建的VO记录
perf: 优化WebSocketClientService中的session关闭逻辑
style: 清理无用导入和注释，统一代码格式

client/src/main/java/com/ecep/contract/service/ContractKindService.java

@@ -11,6 +11,8 @@ import org.springframework.stereotype.Service;
 import com.ecep.contract.vm.ContractKindViewModel;
 import com.ecep.contract.vo.ContractKindVo;
 
+import javafx.util.StringConverter;
+
 @Service
 @CacheConfig(cacheNames = "contract-kind")
 public class ContractKindService extends QueryService<ContractKindVo, ContractKindViewModel> {
@@ -68,4 +70,19 @@ public class ContractKindService extends QueryService<ContractKindVo, ContractKi
         super.delete(entity);
     }
 
+    @Override
+    public StringConverter<ContractKindVo> getStringConverter() {
+        return new StringConverter<ContractKindVo>() {
+            @Override
+            public String toString(ContractKindVo object) {
+                return object.getCode() + " " + object.getName() + " " + object.getTitle();
+            }
+
+            @Override
+            public ContractKindVo fromString(String string) {
+                return findByCode(string);
+            }
+        };
+    }
+
 }