SEO optimization: meta tags, sitemap, robots.txt

[lightRain0629]

Summary

• Added complete SEO meta tags in public/index.html — title, description, keywords, canonical, OpenGraph (og:type, og:site_name, og:image, etc.) and Twitter card tags. All URLs use https:// and the og:image points to logo512.png.
• Added public/sitemap.xml and updated robots.txt to explicitly Allow: / and reference the sitemap.
• Removed the unused react-helmet / @types/react-helmet dependencies — all SEO is now sourced from index.html (single source of truth, works for non-JS crawlers).
• Minor cleanup: removed a stale comment in Footer.tsx and tidied ProductsContent.tsx (structural wrap + dead Radio.Group comments).
• Dropped package-lock.json since the project uses Yarn.

Test plan

• yarn install runs cleanly
• yarn build succeeds
• Page title and meta description visible in index.html source
• Verify OG preview using opengraph.xyz or Facebook sharing debugger after deploy
• Confirm https://bilerdrinks.com/sitemap.xml and /robots.txt are reachable post-deploy
• Visual regression check on the products section (only structural wrapping was changed)