Initial upload of BB-Apartment 2026 website.

Adds the complete Next.js website including i18n routing, house and
apartment pages, Beds24 v2 integration for live availability/pricing,
Stripe checkout, contact forms, Docker setup and deployment docs.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/[locale]/error.tsx

@@ -0,0 +1,33 @@
+"use client";
+
+import { useEffect } from "react";
+
+export default function Error({
+  error,
+  reset,
+}: {
+  error: Error & { digest?: string };
+  reset: () => void;
+}) {
+  useEffect(() => {
+    console.error(error);
+  }, [error]);
+
+  return (
+    <div className="min-h-screen flex flex-col items-center justify-center px-4 text-center">
+      <h2 className="text-2xl font-bold text-brand-grey-dark mb-4">
+        Etwas ist schiefgelaufen.
+      </h2>
+      <p className="text-brand-grey mb-8 max-w-md">
+        {error.message ||
+          "Beim Laden der Seite ist ein Fehler aufgetreten. Bitte versuche es erneut."}
+      </p>
+      <button
+        onClick={reset}
+        className="px-6 py-3 bg-brand-green text-white rounded-xl font-medium hover:bg-brand-green-dark transition-colors"
+      >
+        Erneut versuchen
+      </button>
+    </div>
+  );
+}