chore: switch star history chart to starchart.cc for faster updates

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 24kchengYe

README.md

@@ -820,4 +820,4 @@ IB · Cambridge IGCSE/A-Level · 蒙台梭利 · 华德福 · 瑞吉欧 · 古
 
 ![Visitors](https://visitor-badge.laobi.icu/badge?page_id=24kchengYe.human-skill-tree)
 
-[![Star History Chart](https://api.star-history.com/svg?repos=24kchengYe/human-skill-tree&type=Date)](https://star-history.com/#24kchengYe/human-skill-tree&Date)
+[![Star History](https://starchart.cc/24kchengYe/human-skill-tree.svg)](https://starchart.cc/24kchengYe/human-skill-tree)