Add wishlist feature (frontend), gated by CompanySettings.wishlistEnabled

New: useWishlist.ts (fetch+optimistic-toggle hook, server-backed since
a wishlist needs a logged-in customer, unlike the guest-friendly cart),
WishlistButton.tsx (heart toggle, login-redirects on 401), Navbar's
wishlist icon+badge (hidden below sm: — Account+Cart are the only
always-visible icons on true mobile, a 3rd icon there risks the same
computed nav-overflow class of bug documented in the figma-to-nextjs
skill), and /konto/merkliste (list page, 404s if the feature gets
disabled after a customer already has rows).

Product gained numericId (the raw Payload id) alongside its existing
slug id — WishlistItems.product is a real numeric relationship field,
unlike cart/checkout's slug-keyed "commerce id".

Backend counterpart (WishlistItems collection, CompanySettings toggle,
migration) already deployed separately.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/components/Navbar.tsx

@@ -6,6 +6,7 @@ import Image from "next/image";
 import { usePathname } from "next/navigation";
 import { AnimatePresence, motion } from "motion/react";
 import { useCartCount } from "../lib/cart";
+import { useWishlist } from "../lib/useWishlist";
 import { AUTH_CHANGED_EVENT } from "../lib/auth";
 import { NewsletterModal } from "./NewsletterModal";
 import { useCartFly } from "./CartFly";
@@ -131,6 +132,40 @@ function AccountLink() {
   );
 }
 
+// Wishlist icon + count badge — only rendered by the caller when
+// `wishlistEnabled` (CompanySettings), and even then hidden below `sm:`.
+// Account+Cart are the only always-visible icons on true mobile (see the
+// trailing-controls group's own comment: gap-2 there was already tuned
+// specifically for exactly 2 icons) — a 3rd icon squeezed in at the
+// smallest phone widths risks the exact nav-overflow class of bug
+// documented in the figma-to-nextjs skill (computed hamburger/icon-row
+// thresholds, not assumed ones). sm+ has real room to spare.
+function WishlistLink() {
+  const { count } = useWishlist();
+
+  return (
+    <Link
+      href="/konto/merkliste"
+      aria-label={count > 0 ? `Merkliste, ${count} Artikel` : "Merkliste"}
+      className="relative hidden sm:flex h-11 w-11 items-center justify-center shrink-0 active:scale-[0.9] transition-transform"
+    >
+      <svg viewBox="0 0 20 18" className="h-6 w-6 text-text-primary" fill="none" aria-hidden="true">
+        <path
+          d="M10 17S1 11.5 1 5.8C1 2.6 3.4 1 5.8 1c1.6 0 3.2.9 4.2 2.4C11 1.9 12.6 1 14.2 1 16.6 1 19 2.6 19 5.8 19 11.5 10 17 10 17Z"
+          stroke="currentColor"
+          strokeWidth="1.6"
+          strokeLinejoin="round"
+        />
+      </svg>
+      {count > 0 && (
+        <span className="absolute top-0 right-0 flex h-[18px] min-w-[18px] items-center justify-center rounded-full bg-brand px-1 text-[0.6875rem] font-bold leading-none text-white">
+          {count > 99 ? "99+" : count}
+        </span>
+      )}
+    </Link>
+  );
+}
+
 // Cart icon + count badge — traced from the Figma Navbar/Default component's
 // btn-cart (icon-cart 32x30 + cart-count-badge, node 4849:24). Visible at
 // every breakpoint tier (unlike the nav links / CTA buttons, which move into
@@ -210,7 +245,7 @@ function CartLink() {
   );
 }
 
-export function Navbar({ singleActiveProduct }: { singleActiveProduct: boolean }) {
+export function Navbar({ singleActiveProduct, wishlistEnabled }: { singleActiveProduct: boolean; wishlistEnabled: boolean }) {
   const pathname = usePathname();
   const [scrolled, setScrolled] = useState(false);
   const [activeSection, setActiveSection] = useState("");
@@ -510,6 +545,7 @@ export function Navbar({ singleActiveProduct }: { singleActiveProduct: boolean }
                 these two icons are the only always-visible controls. */}
             <div className="flex items-center">
               <AccountLink />
+              {wishlistEnabled && <WishlistLink />}
               <CartLink />
             </div>
 

app/components/WishlistButton.tsx

@@ -0,0 +1,62 @@
+"use client";
+
+import { useRouter } from "next/navigation";
+import { useState } from "react";
+import { useWishlist } from "../lib/useWishlist";
+
+// Heart-toggle for a product card/detail page. Login-gated (unlike the
+// cart, which works for guests) — a logged-out click redirects to
+// /konto/login?redirect=<back-here> instead of silently failing, since
+// there's no local-storage fallback that would make sense for a wishlist
+// (see useWishlist.ts's own comment on why this can't reuse cart.ts's
+// guest-friendly pattern).
+export function WishlistButton({
+  productId,
+  variant = "",
+  className = "",
+}: {
+  productId: number;
+  variant?: string;
+  className?: string;
+}) {
+  const { isWishlisted, toggle } = useWishlist();
+  const [pending, setPending] = useState(false);
+  const router = useRouter();
+  const wishlisted = isWishlisted(productId, variant);
+
+  async function handleClick(e: React.MouseEvent) {
+    e.preventDefault();
+    e.stopPropagation();
+    if (pending) return;
+
+    const res = await fetch("/api/account/wishlist", { method: "GET", cache: "no-store" });
+    if (res.status === 401) {
+      router.push(`/konto/login?redirect=${encodeURIComponent(window.location.pathname)}`);
+      return;
+    }
+
+    setPending(true);
+    await toggle(productId, variant);
+    setPending(false);
+  }
+
+  return (
+    <button
+      type="button"
+      onClick={handleClick}
+      aria-label={wishlisted ? "Von der Merkliste entfernen" : "Zur Merkliste hinzufügen"}
+      aria-pressed={wishlisted}
+      disabled={pending}
+      className={`flex h-9 w-9 items-center justify-center rounded-full bg-bg-base/90 backdrop-blur-sm transition-transform active:scale-90 disabled:opacity-60 ${className}`}
+    >
+      <svg width="20" height="18" viewBox="0 0 20 18" fill={wishlisted ? "currentColor" : "none"} className={wishlisted ? "text-brand" : "text-text-primary"}>
+        <path
+          d="M10 17S1 11.5 1 5.8C1 2.6 3.4 1 5.8 1c1.6 0 3.2.9 4.2 2.4C11 1.9 12.6 1 14.2 1 16.6 1 19 2.6 19 5.8 19 11.5 10 17 10 17Z"
+          stroke="currentColor"
+          strokeWidth="1.5"
+          strokeLinejoin="round"
+        />
+      </svg>
+    </button>
+  );
+}