feat: Racing Cards landing page - Astro + Tailwind v4

- Mobile-first dark mode landing
- Lucide icons (zero emojis)
- Self-hostable (Dockerfile + nginx)
- 10 card images generated with Nano Banana 2
- Sections: Hero, How It Works, Card Gallery, Features, Early Access, Footer
- Simple HTML form (no Netlify dependency)
- Zero JS output, static HTML

netlify.toml

@@ -0,0 +1,18 @@
+[build]
+  command = "npm run build"
+  publish = "dist"
+
+[build.environment]
+  NODE_VERSION = "22"
+
+[[headers]]
+  for = "/*"
+  [headers.values]
+    X-Frame-Options = "DENY"
+    X-Content-Type-Options = "nosniff"
+    Referrer-Policy = "strict-origin-when-cross-origin"
+
+[[headers]]
+  for = "/_astro/*"
+  [headers.values]
+    Cache-Control = "public, max-age=31536000, immutable"