Add Turnstile protection to user actions

app/(frontend)/termine/[slug]/page.tsx

@@ -25,6 +25,7 @@ import { resolveRedirect } from "@/lib/seo/redirects";
 import { siteConfig } from "@/lib/site";
 
 export const dynamic = "force-dynamic";
+const turnstileSiteKey = process.env.TURNSTILE_SITE_KEY ?? "";
 
 type Args = { params: Promise<{ slug: string }> };
 
@@ -137,7 +138,7 @@ export default async function EventDetailPage({ params }: Args) {
               <div>
                 <h2 className="font-serif text-2xl font-medium text-anouma-plum">Anmeldung</h2>
                 <div className="mt-4 max-w-sm">
-                  <RegisterForm slug={slug} />
+                  <RegisterForm slug={slug} siteKey={turnstileSiteKey} />
                 </div>
               </div>
             )}