Add native cookie consent and move hero intro above CTA

- Restore CookieConsent banner behavior with the new dependency
- Reposition the right-panel intro above the Projekt anfragen button
- Add focused tests and update build metadata

package.json

@@ -30,6 +30,7 @@
     "tailwind-merge": "^3.5.0",
     "tailwindcss": "^4.2.3",
     "tw-animate-css": "^1.4.0",
+    "vanilla-cookieconsent": "^3.1.0",
     "zod": "^4.3.6"
   },
   "devDependencies": {