feat: share image, metadata and icons that match the new site

The link preview used an old template with a blog description. The share
image is now a screenshot of the real hero (scripts/render-share-image.mjs),
served as Open Graph and Twitter image. Title and description come from one
place and are used by the page, the previews and the structured data. Adds an
apple touch icon and removes the old share-image template and its fonts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/public/robots.txt

@@ -1,4 +1,4 @@
 User-agent: *
 Allow: /
 
-Sitemap: https://mintel.me/sitemap.xml
+Sitemap: https://mintel.me/sitemap.xml