Add .gitignore, robots.txt, and sitemap integration

Move and restructure BaseLayout to src/layouts with SEO meta tags Add
404 page with accessibility improvements Restructure pages to src/pages

public/favicon.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
+  <rect width="100" height="100" fill="#1a1410"/>
+  <text x="50" y="70" font-size="60" text-anchor="middle" fill="#d4a574">☕</text>
+</svg>

public/robots.txt

@@ -0,0 +1,16 @@
+# Hidden Den Cafe - Robots.txt
+User-agent: *
+Allow: /
+
+# Sitemap
+Sitemap: https://hiddenden.cafe/sitemap-index.xml
+
+# Crawl-delay for polite crawlers
+Crawl-delay: 1
+
+# Block aggressive bots (optional - uncomment if needed)
+# User-agent: AhrefsBot
+# Disallow: /
+
+# User-agent: SemrushBot
+# Disallow: /