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/CompanyExtendInfoService.java

@@ -0,0 +1,11 @@
+package com.ecep.contract.service;
+
+import com.ecep.contract.model.Company;
+import com.ecep.contract.model.CompanyExtendInfo;
+import com.ecep.contract.vm.CompanyExtendInfoViewModel;
+
+public class CompanyExtendInfoService implements ViewModelService<CompanyExtendInfo, CompanyExtendInfoViewModel> {
+    public CompanyExtendInfo findByCompany(Company company) {
+        throw new UnsupportedOperationException("Unimplemented method 'findByCompany'");
+    }
+}