PDP breadcrumbs: read the real product name instead of hardcoded copy

der-eine's breadcrumb hardcoded "Der Eine" — missing the trailing period
its own headline/pricing card already style in brand color. Switched all
three PDP breadcrumbs to the actual product.name via ProductName so they
can't drift from the real title again.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J1Hu5bZ1kZUgKhab6yNwCt

app/der-eine/components/Hero.tsx

@@ -2,6 +2,7 @@ import Link from "next/link";
 import { AddToCartButton } from "../../components/AddToCartButton";
 import { ProductGallery } from "../../components/ProductGallery";
 import { Reveal } from "../../components/Reveal";
+import { ProductName } from "../../components/ProductName";
 import { getProductBySlug, getShippingSettings, getDefaultTaxRatePercent, getKleinunternehmer } from "../../lib/payload";
 import { formatPrice, discountPercent } from "../../lib/format";
 import { effectiveTaxRate } from "../../lib/cartTotals";
@@ -52,7 +53,7 @@ export async function Hero() {
               Werkzeuge
             </Link>
             <span>›</span>
-            <span className="text-text-primary">Der Eine</span>
+            <span className="text-text-primary">{product ? <ProductName name={product.name} /> : "Der Eine."}</span>
           </p>
 
           <div className="flex flex-col gap-6 items-start w-full flex-1 lg:justify-center">