Add git last modified date tracking for sitemap URLs to provide more accurate lastmod timestamps
Only write sitemap file when content actually changes to avoid unnecessary updates
- Add sitemap generator script that scans markdown files and creates multilingual sitemap
- Update build script to include sitemap generation
- Add robots.txt and llms.txt files for crawlers
- Enhance SEO metadata with better structured data and hreflang tags
- Fix stage-0 URL in README
sanbuphy