Add Everforest theme credits + optimize demo GIF

- Credit sainnhe/everforest for the beautiful color scheme
- Compress demo GIF: 4.6MB → 1.9MB (59% reduction)
- Better loading experience for README viewers

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

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

Author: gitcoder89431

README.md

@@ -211,6 +211,10 @@ This modular design allows the same AI capabilities to power multiple interfaces
 
 MIT License - see [LICENSE](LICENSE) for details.
 
+## Credits
+
+**UI Theme:** Everforest color scheme by [sainnhe](https://github.com/sainnhe/everforest) - A comfortable and pleasant green forest color scheme.
+
 ## Contributing
 
 Built with constitutional Rust patterns and love. Issues and PRs welcome!