Implement SEO, Open Graph, RSS Feed, and Sitemap support

[enesthedev]

We need to improve discoverability and sharing by adding basic SEO metadata, Open Graph tags, an RSS feed, and a sitemap. Each page should include dynamic <title> and tags, along with Open Graph properties like og:title, og:description, and og:image for rich previews on social media. We should generate an RSS feed (/rss.xml) that lists recent posts and a sitemap.xml that indexes all public pages with their last modified dates. Both feeds must update automatically on each build or deploy to keep content fresh.