fix: message created at wrong value

Author: namchuai

engine/services/message_service.cc

@@ -33,7 +33,7 @@ cpp::result<OpenAi::Message, std::string> MessageService::CreateMessage(
   OpenAi::Message msg;
   msg.id = msg_id;
   msg.object = "thread.message";
-  msg.created_at = 0;
+  msg.created_at = seconds_since_epoch;
   msg.thread_id = thread_id;
   msg.status = OpenAi::Status::COMPLETED;
   msg.completed_at = seconds_since_epoch;