Add SEO optimization

- Add meta tags (keywords, author, robots, canonical)
- Add Open Graph tags for social sharing
- Add Twitter card meta tags
- Add hreflang tags for EN/FR language alternates
- Add Schema.org structured data (JSON-LD)
- Create sitemap.xml
- Create robots.txt
- Add workflow documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sitemap.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+        xmlns:xhtml="http://www.w3.org/1999/xhtml">
+  <url>
+    <loc>https://atomaste.com/</loc>
+    <xhtml:link rel="alternate" hreflang="en" href="https://atomaste.com/"/>
+    <xhtml:link rel="alternate" hreflang="fr" href="https://atomaste.com/fr.html"/>
+    <lastmod>2026-01-02</lastmod>
+    <changefreq>monthly</changefreq>
+    <priority>1.0</priority>
+  </url>
+  <url>
+    <loc>https://atomaste.com/fr.html</loc>
+    <xhtml:link rel="alternate" hreflang="en" href="https://atomaste.com/"/>
+    <xhtml:link rel="alternate" hreflang="fr" href="https://atomaste.com/fr.html"/>
+    <lastmod>2026-01-02</lastmod>
+    <changefreq>monthly</changefreq>
+    <priority>0.9</priority>
+  </url>
+</urlset>