fix(service): 修复聊天消息排序逻辑

在分页查询消息时，先按时间升序再按ID升序，确保顺序稳定一致

src/main/java/com/yolo/keyborad/service/impl/KeyboardAiChatMessageServiceImpl.java

@@ -46,7 +46,8 @@ public class KeyboardAiChatMessageServiceImpl extends ServiceImpl<KeyboardAiChat
         queryWrapper.eq(KeyboardAiChatMessage::getUserId, userId)
                 .eq(KeyboardAiChatMessage::getCompanionId, companionId)
                 .eq(KeyboardAiChatMessage::getSessionId, activeSession.getId())
-                .orderByDesc(KeyboardAiChatMessage::getCreatedAt);
+                .orderByAsc(KeyboardAiChatMessage::getCreatedAt)
+                .orderByAsc(KeyboardAiChatMessage::getId);
         IPage<KeyboardAiChatMessage> entityPage = this.page(page, queryWrapper);
         return entityPage.convert(entity -> BeanUtil.copyProperties(entity, ChatMessageHistoryVO.class));
     }