feat: 新增多个服务类及工具类，重构部分代码结构

重构服务类结构，将分散的服务统一整合到service包下
新增ProjectConstant常量类及多个实体服务类
添加SecurityUtils安全工具类和BeanCacher工具类
优化部分UI控件和转换器的实现

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

@@ -1,8 +1,29 @@
 package com.ecep.contract.service;
 
+import java.util.List;
+import java.util.Map;
+
+import com.ecep.contract.ContractFileType;
+import com.ecep.contract.model.Contract;
 import com.ecep.contract.model.ContractFile;
+import com.ecep.contract.model.ContractFileTypeLocal;
 import com.ecep.contract.vm.ContractFileViewModel;
 
 public class ContractFileService implements ViewModelService<ContractFile, ContractFileViewModel> {
 
+    public List<ContractFile> findAllByContract(Contract contract) {
+        // TODO Auto-generated method stub
+        throw new UnsupportedOperationException("Unimplemented method 'findAllByContract'");
+    }
+
+    public Map<ContractFileType, ContractFileTypeLocal> findAllFileTypes(String languageTag) {
+        // TODO Auto-generated method stub
+        throw new UnsupportedOperationException("Unimplemented method 'findAllFileTypes'");
+    }
+
+    public List<ContractFile> findAllByContractAndFileType(Contract contract, ContractFileType type) {
+        // TODO Auto-generated method stub
+        throw new UnsupportedOperationException("Unimplemented method 'findAllByContractAndFileType'");
+    }
+
 }