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>

astro.config.mjs

@@ -0,0 +1,13 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+import tailwind from '@astrojs/tailwind';
+
+// https://astro.build/config
+export default defineConfig({
+  integrations: [tailwind()],
+  output: 'static',
+  i18n: {
+    defaultLocale: 'de',
+    locales: ['de'],
+  },
+});