feat(integration): 添加 ZT-Message Kafka 生产者集成

- 新增 ZtMessage DTO 类用于消息体
- 实现 ZtMessageProducerService 生产者服务
- 添加示例演示如何发送消息
- 更新配置文件和文档以支持新功能

src/main/java/com/ycwl/basic/integration/kafka/config/KafkaIntegrationProperties.java

@@ -11,6 +11,7 @@ public class KafkaIntegrationProperties {
 
     private boolean enabled = false;
     private String bootstrapServers = "100.64.0.12:39092";
+    private String ztMessageTopic = "zt-message"; // topic for zt-message microservice
     private Consumer consumer = new Consumer();
     private Producer producer = new Producer();