codician/diffinerypublic

Add a proper favicon, app icons and search metadata (#8)

Every page now links /favicon.ico (16-64px, Google needs a multiple of
48px), an SVG favicon, PNG and Apple touch icons and a web manifest, plus
a meta description, canonical URL, Open Graph and Twitter cards with a
1200x630 preview image. The home page carries WebSite and Organization
structured data. robots.txt now allows crawling of public pages and points
at a sitemap of the home page and public repositories; sign-in, settings
and other private pages are marked noindex.


Claude-Session: https://claude.ai/code/session_01AizKXSsengXZRegJxRATkL

Co-authored-by: Claude <noreply@anthropic.com>