Add SEO files: robots, sitemap, llms.txt

[devaraj3]

What changed

• Added public/robots.txt allowing all crawlers and pointing to the sitemap
• Added public/sitemap.xml listing the / and /viewer routes
• Added public/llms.txt describing the app for AI/LLM crawlers
• Added public/og-image.png (1200x630 screenshot) for social link previews
• Updated index.html: added JSON-LD SoftwareApplication structured data, canonical link, og:url / og:type / og:image (+ dimensions), twitter:card tags, and a more descriptive <title>

Why

• The live site currently has no robots.txt, sitemap, or structured data, and isn't indexed by any search engine yet
• These are the foundational files Google, Bing, and AI/LLM crawlers look for to understand and rank the site
• Purely metadata and static files — no changes to app logic or UI

Validation

• npm run lint
• npm run typecheck
• npm run build

Notes

• No visual or functional changes to the CAD viewer itself
• After this merges and deploys, verify live at /robots.txt, /sitemap.xml, /llms.txt, and /og-image.png
• og-image.png should be refreshed with a new screenshot if the landing page design changes significantly later

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
cad-viewer	Ready	Preview, Comment	Jul 25, 2026 4:02pm