fix(iot): 修复JT808业务消息重复应答问题

- 在 handleBusinessMessage 中设置 message.setCode(0) 标记协议层已应答
- 避免业务层重复发送 reply 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

@@ -113,7 +113,11 @@ public class Jt808ProtocolHandler extends AbstractProtocolHandler {
                                       String codecType, NetSocket socket,
                                       String productKey, String deviceName, String serverId) {
         try {
-            // 1. 发送消息到消息总线
+            // 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);
+
+            // 2. 发送消息到消息总线
             deviceMessageService.sendDeviceMessage(message, productKey, deviceName, serverId);
 
             log.info("[handleBusinessMessage][JT808 业务消息已发送，clientId: {}, method: {}, messageId: {}]",