fix(iot-gateway): JT808协议使用skipReply标记协议层已应答

- Jt808ProtocolHandler 使用 setSkipReply(true) 替代 setCode(0)
- 避免业务层重复发送回复消息

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

viewsh-module-iot/viewsh-module-iot-gateway/src/main/java/com/viewsh/module/iot/gateway/protocol/tcp/handler/Jt808ProtocolHandler.java

@@ -114,8 +114,8 @@ public class Jt808ProtocolHandler extends AbstractProtocolHandler {
                                       String productKey, String deviceName, String serverId) {
         try {
             // 1. 标记消息为"协议层已应答"，业务层无需再发送 reply
-            // 设置 code = 0 后，isReplyMessage() 返回 true，业务层跳过 reply
-            message.setCode(0);
+            // 设置 skipReply = true 后，业务层跳过 reply
+            message.setSkipReply(true);
 
             // 2. 发送消息到消息总线
             deviceMessageService.sendDeviceMessage(message, productKey, deviceName, serverId);