ping_pong rand() is not seeded so device ids are likely the same across nodes

還沒有人認領這個 Issue。

## Issue template

- Hardware description: docker only
- RTOS: N/A
- Installation type: a containerized version of https://micro.ros.org/docs/tutorials/core/first_application_linux/
- Version or commit hash: b86db303dd7aed7ed34de2e1c2f94300c2ba7e4e
+ this patch to fix the stack corruption https://github.com/micro-ROS/micro-ROS-demos/pull/96

#### Steps to reproduce the issue
Build this repo on your target
```
cd /ros2_ws
. /opt/ros/humble/setup.bash
. install/local_setup.bash
colcon build --packages-select micro_ros_demos_rclc
/ros2_ws/install/micro_ros_demos_rclc/lib/micro_ros_demos_rclc/ping_pong
```

#### Expected behavior
I expect to see ping/pong messages

#### Actual behavior

You will see only Ping or only Pong messages

#### Additional information
Running on Ubuntu 24.04 host, docker compose driving a pair of containers to pubsub.

---

In my testing, seeding random with a nanosecond clock is sufficient to generate different device ids. I'd file a PR but I'd like to see if this was intended or maybe just an artifact of launching two container simultaneously

從 micro_ros_demos_rclc 套件中的 ping_pong 可執行檔開始，追蹤其裝置 ID 與 rand() 狀態的初始化方式。使用提供的 colcon 建置命令和容器命令重現該問題，然後驗證兩個容器是否使用不同的 ID 交換 Ping 和 Pong 訊息。

由索引模型根據 Issue 內容生成。