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

astro.config.mjs

@@ -0,0 +1,9 @@
+import { defineConfig } from 'astro/config';
+import tailwindcss from '@tailwindcss/vite';
+
+export default defineConfig({
+  output: 'static',
+  vite: {
+    plugins: [tailwindcss()],
+  },
+});