fix: 节点更新时serverIpV4/V6/域名字段无法正确清空的问题

使用LambdaUpdateWrapper替代updateById以确保null值能正确更新到数据库

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

springboot-backend/src/main/java/com/admin/service/impl/NodeServiceImpl.java

@@ -15,6 +15,7 @@ import com.admin.service.*;
 import com.alibaba.fastjson.JSONArray;
 import com.alibaba.fastjson.JSONObject;
 import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
+import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;
 import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
 import lombok.extern.slf4j.Slf4j;
@@ -142,10 +143,26 @@ public class NodeServiceImpl extends ServiceImpl<NodeMapper, Node> implements No
 
 
 
-        Node updateNode = buildUpdateNode(nodeUpdateDto);
+        Node updateNode = buildUpdateNode(nodeUpdateDto);
-        this.updateById(updateNode);
+        // Use LambdaUpdateWrapper to explicitly set nullable fields (serverIpV4/V6)
-        return R.ok();
+        // because updateById() skips null fields by default
-    }
+        LambdaUpdateWrapper<Node> wrapper = new LambdaUpdateWrapper<>();
+        wrapper.eq(Node::getId, updateNode.getId())
+               .set(Node::getName, updateNode.getName())
+               .set(Node::getServerIp, updateNode.getServerIp())
+               .set(Node::getServerIpV4, updateNode.getServerIpV4())
+               .set(Node::getServerIpV6, updateNode.getServerIpV6())
+               .set(Node::getPort, updateNode.getPort())
+               .set(Node::getHttp, updateNode.getHttp())
+               .set(Node::getTls, updateNode.getTls())
+               .set(Node::getSocks, updateNode.getSocks())
+               .set(Node::getInterfaceName, updateNode.getInterfaceName())
+               .set(Node::getTcpListenAddr, updateNode.getTcpListenAddr())
+               .set(Node::getUdpListenAddr, updateNode.getUdpListenAddr())
+               .set(Node::getUpdatedTime, updateNode.getUpdatedTime());
+        this.update(wrapper);
+        return R.ok();
+    }
 
     @Override
     public R deleteNode(Long id) {