docs: add GitHub Star History chart to README

Add star-history.com visualization to showcase repository growth and momentum.

Changes:
- Added Star History Chart section before final call-to-action
- Uses star-history.com API for automatic updates
- Clickable chart links to interactive star-history.com page
- Shows repository credibility and growth trajectory

Benefits:
- Social proof for new visitors
- Demonstrates project momentum
- Encourages more stars
- Professional touch to README

Positioned strategically after "Sharing Your Success" section for
maximum visibility and impact.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -1675,6 +1675,12 @@ Using these skills successfully? I'd love to hear about it:
 
 ---
 
+## ⭐ Star History
+
+[![Star History Chart](https://api.star-history.com/svg?repos=alirezarezvani/claude-skills&type=Date)](https://star-history.com/#alirezarezvani/claude-skills&Date)
+
+---
+
 <div align="center">
 
 **⭐ Star this repository** if you find these skills useful!