FanBox 宣传位更新：主 slogan 改为「Coding Agent 的驾驶舱」+ banner 换 .jpg

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -267,6 +267,6 @@ MIT License © [花叔 Huashu](https://github.com/alchaincyf)
 <div align="center">
 <sub>作者的其他项目 · also by 花叔</sub>
 
-[![FanBox · 看得见的 vibe coding](https://raw.githubusercontent.com/alchaincyf/fanbox/master/assets/promo-banner.png)](https://github.com/alchaincyf/fanbox)
+[![FanBox · Coding Agent 的驾驶舱](https://raw.githubusercontent.com/alchaincyf/fanbox/master/assets/promo-banner.jpg)](https://github.com/alchaincyf/fanbox)
 
 </div>