- Fix broken hreflang: /en/ ghost page removed, all hreflang point to canonical /
- Add canonical URL tag
- Remove emoji from page titles
- Rewrite title/description with target keywords (LaTeX OCR, math formula recognition, handwriting math)
- Add JSON-LD WebApplication structured data schema
- Update og:image to clean URL without OSS params, add og:image dimensions
- Fix favicon reference from vite.svg to favicon.png
- Add public/sitemap.xml with hreflang annotations
- Add public/robots.txt pointing to sitemap
- Update seoHelper.ts keywords for both zh/en to match search intent
- Add CLAUDE.md project documentation
