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/types.d.ts

@@ -0,0 +1,2 @@
+/// <reference types="astro/client" />
+/// <reference path="content.d.ts" />