feat: add /bestellbestaetigung order confirmation page

Matches the Figma mockup (checkmark hero, order summary card,
delivery-status panel, testimonial band) with the checkout's 4-step
bar inserted (all steps done) and the "Bis dahin: Lass dich
inspirieren" block omitted, per request.

Extracted the step bar into a shared CheckoutSteps component so
/checkout and /bestellbestaetigung don't duplicate it. The actually-
selected shipping cost and payment method are captured into a
sessionStorage snapshot by /checkout's "Jetzt kaufen" click (there's
no real order backend, so this click is what "placing the order"
means here) and read back on the confirmation page — not just
defaulted to the first active method of each, so the receipt matches
what the shopper actually picked. Also tightened the checkout
newsletter-consent copy ("Wenn du zustimmst" instead of "Wenn du
oben zustimmst").

app/bestellbestaetigung/page.tsx

@@ -0,0 +1,28 @@
+import type { Metadata } from "next";
+import { BestellbestaetigungContent } from "./components/BestellbestaetigungContent";
+import { TrustRow } from "../components/TrustRow";
+import { Footer } from "../components/Footer";
+
+// robots: noindex — transactional page, same reasoning as /cart and
+// /checkout (this one doubles as a receipt, not something to surface in
+// search results).
+export const metadata: Metadata = {
+  title: "Bestellbestätigung",
+  description: "Deine Bestellung bei einfach produktiv wurde erfolgreich aufgegeben.",
+  robots: {
+    index: false,
+    follow: true,
+  },
+};
+
+export default function BestellbestaetigungPage() {
+  return (
+    <>
+      <main className="flex flex-col flex-1 bg-bg-base">
+        <BestellbestaetigungContent />
+        <TrustRow />
+      </main>
+      <Footer />
+    </>
+  );
+}