Initial Astro + Tailwind scaffold for Wohlruf landing page

- Astro static site generator with zero-JS default output
- Tailwind CSS for styling (consistent with main app stack)
- German-language landing page: hero, how-it-works, features, pricing, FAQ, CTA
- Placeholder pages for Impressum, Datenschutz, AGB
- Reusable Header/Footer/Base layout components
- FTP-deployable static output via `npm run build`
- README with content TODO list for CMO

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tailwind.config.mjs

@@ -0,0 +1,12 @@
+/** @type {import('tailwindcss').Config} */
+export default {
+  content: ['./src/**/*.{astro,html,js,jsx,md,mdx,svelte,ts,tsx,vue}'],
+  theme: {
+    extend: {
+      fontFamily: {
+        sans: ['system-ui', '-apple-system', 'BlinkMacSystemFont', 'Segoe UI', 'sans-serif'],
+      },
+    },
+  },
+  plugins: [],
+};