Add shop, cart, versand pages and Impulse & Tipps detail page

- New /shop overview, /cart (real cart state via useSyncExternalStore),
  /versand (shipping policy page with TOC) and /newsletter detail page
- Cart: quantity/removal, order summary, related-products cross-sell
  with randomized picks, VersandModal quick-reference instead of
  navigating away, MwSt. disclosure next to unit prices
- Add-to-cart UX: inline success feedback (green state) plus a
  fly-to-navbar-cart-icon animation (CartFlyProvider) with a delayed
  badge count-up; AddToCartButton no longer navigates straight to /cart
- Shared lib/products.ts catalog and lib/shipping.ts constants (cost,
  free-shipping threshold, handling/transit days) so cart, trust badges
  and the versand page can never drift apart
- Fix Navbar smooth-scroll easing (ease-out instead of ease-in-out, no
  more perceived start delay); compress newsletter modal photo
  2.4MB -> 85KB to fix first-open jank

app/versand/page.tsx

@@ -0,0 +1,46 @@
+import type { Metadata } from "next";
+import Link from "next/link";
+import { Reveal } from "../components/Reveal";
+import { Footer } from "../components/Footer";
+import { VersandSections } from "./components/VersandSections";
+import { VersandTOC } from "./components/VersandTOC";
+
+export const metadata: Metadata = {
+  title: "Versand",
+  description:
+    "Versandkosten, Lieferzeiten und Liefergebiet für Bestellungen bei einfach produktiv.",
+  alternates: { canonical: "/versand" },
+};
+
+export default function VersandPage() {
+  return (
+    <>
+      <main className="flex flex-col flex-1 bg-bg-base">
+        <Reveal className="flex flex-col gap-3 items-start pb-6 pt-10 px-[var(--layout-padding-x)] w-full">
+          <p className="flex items-center gap-2 text-body-sm text-text-muted">
+            <Link href="/" className="hover:text-brand transition-colors">Startseite</Link>
+            <span>›</span>
+            <span className="text-text-primary">Versand</span>
+          </p>
+          <p
+            className="font-semibold text-h-feature text-text-primary"
+            style={{ fontFamily: "var(--font-lora)" }}
+          >
+            Versand
+          </p>
+          <p className="text-body text-text-muted">
+            Transparent, fair und pünktlich — alles zu Kosten, Lieferzeiten und Liefergebiet.
+          </p>
+        </Reveal>
+
+        <div className="flex flex-col lg:flex-row gap-8 lg:gap-12 items-start pb-16 pt-2 px-[var(--layout-padding-x)] w-full">
+          <VersandTOC />
+          <div className="w-full lg:flex-1 max-w-[45rem]">
+            <VersandSections withAnchors />
+          </div>
+        </div>
+      </main>
+      <Footer />
+    </>
+  );
+}