[ImgBot] Optimize images (#323)

*Total -- 348.01kb -> 301.43kb (13.38%)

/assets/publications/2025-tempo_thumb.png -- 159.28kb -> 122.68kb (22.98%)
/assets/people/ziyong.jpg -- 188.73kb -> 178.75kb (5.29%)

Signed-off-by: ImgBotApp <[email protected]>
Co-authored-by: ImgBotApp <[email protected]>

Author: imgbot[bot]