feat: 实现员工同步任务的WebSocket支持及合同名称锁定功能

- 为EmployeesSyncTask添加WebSocket客户端和服务端支持，实现实时任务进度反馈
- 新增合同名称锁定功能，防止误修改重要合同名称
- 优化SmbFileService的连接异常处理，提高稳定性
- 重构ContractFilesRebuildTasker的任务执行逻辑，改进错误处理
- 更新tasker_mapper.json注册EmployeesSyncTask
- 添加相关任务文档和验收报告

修复WebSocketClientSession的任务完成状态处理问题
改进UITools中任务执行的线程管理
优化DepartmentService的findByCode方法返回类型

client/src/main/java/com/ecep/contract/WebSocketClientSession.java

@@ -1,22 +1,19 @@
 package com.ecep.contract;
 
+import com.ecep.contract.constant.WebSocketConstant;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import lombok.Getter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.BeanUtils;
+
 import java.beans.PropertyDescriptor;
 import java.util.Locale;
 import java.util.Map;
 import java.util.UUID;
 import java.util.logging.Level;
 
-import javafx.application.Platform;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.beans.BeanUtils;
-
-import com.ecep.contract.constant.WebSocketConstant;
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JsonNode;
-
-import lombok.Getter;
-
 /**
  *
  */
@@ -27,6 +24,8 @@ public class WebSocketClientSession {
      */
     @Getter
     private final String sessionId = UUID.randomUUID().toString();
+    @Getter
+    private boolean done = false;
 
     private WebSocketClientTasker tasker;
 
@@ -69,6 +68,8 @@ public class WebSocketClientSession {
                 handleAsStart(args);
             } else if (type.equals("done")) {
                 handleAsDone(args);
+                done = true;
+                close();
             } else {
                 tasker.updateMessage(java.util.logging.Level.INFO, "未知的消息类型: " + node.toString());
             }
@@ -83,7 +84,6 @@ public class WebSocketClientSession {
 
     private void handleAsDone(JsonNode args) {
         tasker.updateMessage(java.util.logging.Level.INFO, "任务完成");
-        close();
     }
 
     private void handleAsProgress(JsonNode args) {