feat(rental): Sprint D — panier + checkout + intégration carbet

Cart lib + cookie persistence (karbe-rental-cart, 30j) avec context React
useCart(). Provider wrappé dans layout pour hydratation server→client.

Page /panier :
- Récap regroupé par prestataire (sous-totaux, caution)
- Édition lignes (dates, qté), suppression, vider panier
- Bouton « Valider et payer » → POST /api/rentals/checkout
- Badge 🛒 dans SiteHeader avec total items

Composant <AddToCart /> sur /materiel/[itemId] avec date picker + qté.

API POST /api/rentals/checkout :
- Validation auth + items actifs + provider approved + qté/dates
- Transaction Prisma : recheck stock par fenêtre + crée 1 RentalBooking
  par prestataire + RentalLines (snapshot prix) + RentalItemAvailability
  (blocage des dispos)
- Calcul commissionAmount selon provider.commissionPct
- Si Stripe activé : Checkout Session unique avec 1 line_item par
  RentalBooking, metadata {type:"rental-bundle", rentalBookingIds:[]}
- Sinon : crée en PENDING, retourne rentalBookingIds
- Vide le cookie panier après création
- Audit log rental.checkout.created

Webhook Stripe étendu :
- checkout.session.completed type=rental-bundle → CONFIRMED+SUCCEEDED
  sur toutes les RentalBookings du bundle
- payment_intent.payment_failed metadata.rentalBookingIds → CANCELLED
  + supprime les RentalItemAvailability (libère le stock)

Intégration carbet :
- /carbets/[slug] : panneau « Compléter votre séjour » avec items des
  prestataires de la même rivière + System D (recommandation contextuelle)
- /reservations/[id] : section « Matériel associé » listant les
  RentalBookings liées
- /mes-locations : page récap toutes les locations (System D + tiers,
  liées carbet ou standalone)
- Lien « Mes locations » dans SiteHeader

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/panier/_components/CartReview.tsx

@@ -0,0 +1,249 @@
+"use client";
+
+import { useMemo, useState, useTransition } from "react";
+import Link from "next/link";
+import { useRouter } from "next/navigation";
+
+import { useCart } from "@/components/RentalCartProvider";
+import { diffDays } from "@/lib/rental-cart";
+
+type ItemSnapshot = {
+  id: string;
+  name: string;
+  category: string;
+  imageUrl: string | null;
+  pricePerDay: string;
+  deposit: string;
+  totalQty: number;
+  provider: { id: string; name: string; isSystemD: boolean };
+};
+
+type Line = {
+  idx: number;
+  entry: { itemId: string; qty: number; startDate: string; endDate: string };
+  item: ItemSnapshot;
+};
+
+export function CartReview({ lines }: { lines: Line[] }) {
+  const router = useRouter();
+  const { removeEntry, updateEntry, clear } = useCart();
+  const [busy, startTransition] = useTransition();
+  const [error, setError] = useState<string | null>(null);
+
+  // Groupe par prestataire
+  const groups = useMemo(() => {
+    const map = new Map<string, { providerName: string; isSystemD: boolean; lines: Line[]; subtotal: number; deposit: number }>();
+    for (const l of lines) {
+      const nights = Math.max(1, diffDays(l.entry.startDate, l.entry.endDate));
+      const lineSub = nights * l.entry.qty * Number(l.item.pricePerDay);
+      const lineDeposit = l.entry.qty * Number(l.item.deposit);
+      const existing = map.get(l.item.provider.id);
+      if (existing) {
+        existing.lines.push(l);
+        existing.subtotal += lineSub;
+        existing.deposit += lineDeposit;
+      } else {
+        map.set(l.item.provider.id, {
+          providerName: l.item.provider.name,
+          isSystemD: l.item.provider.isSystemD,
+          lines: [l],
+          subtotal: lineSub,
+          deposit: lineDeposit,
+        });
+      }
+    }
+    return Array.from(map.values());
+  }, [lines]);
+
+  const grandTotal = groups.reduce((acc, g) => acc + g.subtotal, 0);
+  const grandDeposit = groups.reduce((acc, g) => acc + g.deposit, 0);
+
+  function checkout() {
+    setError(null);
+    startTransition(async () => {
+      const res = await fetch("/api/rentals/checkout", { method: "POST" });
+      const json = await res.json().catch(() => ({}));
+      if (!res.ok) {
+        setError(json?.error || `Erreur ${res.status}`);
+        return;
+      }
+      if (json.checkoutUrl) {
+        window.location.assign(json.checkoutUrl);
+        return;
+      }
+      if (json.rentalBookingIds?.length) {
+        clear();
+        router.push(`/mes-locations?ok=${json.rentalBookingIds[0]}`);
+        return;
+      }
+      router.push("/mes-locations");
+    });
+  }
+
+  return (
+    <div className="space-y-6">
+      {groups.map((g) => (
+        <section key={g.providerName} className="rounded-lg border border-zinc-200 bg-white shadow-sm">
+          <header className="border-b border-zinc-100 px-4 py-3">
+            <h2 className="text-base font-semibold text-zinc-900">
+              {g.providerName}
+              {g.isSystemD ? (
+                <span className="ml-2 rounded-full bg-emerald-600 px-2 py-0.5 text-[10px] font-semibold uppercase tracking-wider text-white">
+                  Karbé
+                </span>
+              ) : null}
+            </h2>
+          </header>
+          <ul className="divide-y divide-zinc-100">
+            {g.lines.map((l) => (
+              <CartLineItem
+                key={l.idx}
+                line={l}
+                onRemove={() => removeEntry(l.idx)}
+                onChangeQty={(qty) => updateEntry(l.idx, { qty })}
+                onChangeDates={(startDate, endDate) => updateEntry(l.idx, { startDate, endDate })}
+                disabled={busy}
+              />
+            ))}
+          </ul>
+          <footer className="flex items-center justify-between border-t border-zinc-100 bg-zinc-50 px-4 py-2 text-sm">
+            <span className="text-zinc-600">Sous-total prestataire</span>
+            <span className="font-mono font-semibold text-zinc-900">{g.subtotal.toFixed(2)} €</span>
+          </footer>
+        </section>
+      ))}
+
+      <aside className="sticky bottom-3 z-10 rounded-lg border border-zinc-200 bg-white p-4 shadow-md">
+        <dl className="space-y-1 text-sm">
+          <div className="flex justify-between">
+            <dt>Total location</dt>
+            <dd className="font-mono font-semibold">{grandTotal.toFixed(2)} €</dd>
+          </div>
+          {grandDeposit > 0 ? (
+            <div className="flex justify-between text-xs text-zinc-500">
+              <dt>+ Caution récupérable</dt>
+              <dd className="font-mono">{grandDeposit.toFixed(2)} €</dd>
+            </div>
+          ) : null}
+          <div className="flex justify-between border-t border-zinc-100 pt-2 text-base font-semibold text-zinc-900">
+            <dt>À régler</dt>
+            <dd className="font-mono">{(grandTotal + grandDeposit).toFixed(2)} €</dd>
+          </div>
+        </dl>
+
+        {error ? (
+          <div className="mt-2 rounded border border-rose-200 bg-rose-50 px-3 py-1.5 text-xs text-rose-700">
+            {error}
+          </div>
+        ) : null}
+
+        <div className="mt-3 flex flex-wrap items-center justify-between gap-2">
+          <button
+            type="button"
+            onClick={clear}
+            disabled={busy}
+            className="text-xs text-zinc-500 hover:text-zinc-900"
+          >
+            Vider le panier
+          </button>
+          <button
+            type="button"
+            onClick={checkout}
+            disabled={busy || lines.length === 0}
+            className="rounded-md bg-emerald-600 px-5 py-2 text-sm font-semibold text-white hover:bg-emerald-700 disabled:opacity-50"
+          >
+            {busy ? "Envoi…" : "Valider et payer"}
+          </button>
+        </div>
+        <p className="mt-2 text-center text-[11px] text-zinc-500">
+          Vous devez être <Link href="/connexion?next=/panier" className="underline">connecté</Link> pour finaliser.
+        </p>
+      </aside>
+    </div>
+  );
+}
+
+function CartLineItem({
+  line,
+  onRemove,
+  onChangeQty,
+  onChangeDates,
+  disabled,
+}: {
+  line: Line;
+  onRemove: () => void;
+  onChangeQty: (qty: number) => void;
+  onChangeDates: (start: string, end: string) => void;
+  disabled?: boolean;
+}) {
+  const nights = Math.max(1, diffDays(line.entry.startDate, line.entry.endDate));
+  const lineTotal = nights * line.entry.qty * Number(line.item.pricePerDay);
+  return (
+    <li className="flex flex-wrap items-center gap-3 px-4 py-3">
+      <div className="hidden h-14 w-20 shrink-0 overflow-hidden rounded bg-zinc-100 sm:block">
+        {line.item.imageUrl ? (
+          // eslint-disable-next-line @next/next/no-img-element
+          <img src={line.item.imageUrl} alt={line.item.name} className="h-full w-full object-cover" />
+        ) : (
+          <div className="flex h-full items-center justify-center text-2xl text-zinc-300">
+            {line.item.category === "SLEEP" ? "💤" :
+             line.item.category === "NAVIGATION" ? "🛶" :
+             line.item.category === "FISHING" ? "🎣" :
+             line.item.category === "COOKING" ? "🍳" : "🦺"}
+          </div>
+        )}
+      </div>
+      <div className="flex-1 min-w-0">
+        <Link href={`/materiel/${line.item.id}`} className="font-medium text-zinc-900 hover:underline">
+          {line.item.name}
+        </Link>
+        <div className="mt-1 grid grid-cols-2 gap-1 text-xs sm:grid-cols-4">
+          <label className="block">
+            <span className="text-zinc-500">Du</span>
+            <input
+              type="date"
+              value={line.entry.startDate}
+              onChange={(e) => onChangeDates(e.target.value, line.entry.endDate)}
+              disabled={disabled}
+              className="block w-full rounded border border-zinc-200 px-1.5 py-0.5"
+            />
+          </label>
+          <label className="block">
+            <span className="text-zinc-500">Au</span>
+            <input
+              type="date"
+              value={line.entry.endDate}
+              onChange={(e) => onChangeDates(line.entry.startDate, e.target.value)}
+              disabled={disabled}
+              className="block w-full rounded border border-zinc-200 px-1.5 py-0.5"
+            />
+          </label>
+          <label className="block">
+            <span className="text-zinc-500">Qté</span>
+            <input
+              type="number"
+              min={1}
+              max={line.item.totalQty}
+              value={line.entry.qty}
+              onChange={(e) => onChangeQty(Math.max(1, Math.min(line.item.totalQty, Number(e.target.value) || 1)))}
+              disabled={disabled}
+              className="block w-full rounded border border-zinc-200 px-1.5 py-0.5"
+            />
+          </label>
+          <div className="flex flex-col text-right">
+            <span className="text-zinc-500">{nights} j × {Number(line.item.pricePerDay).toFixed(0)} €</span>
+            <span className="font-mono font-semibold text-zinc-900">{lineTotal.toFixed(2)} €</span>
+          </div>
+        </div>
+      </div>
+      <button
+        type="button"
+        onClick={onRemove}
+        disabled={disabled}
+        className="text-xs text-rose-700 hover:text-rose-900 disabled:opacity-50"
+      >
+        Retirer
+      </button>
+    </li>
+  );
+}

src/app/panier/page.tsx

@@ -0,0 +1,81 @@
+import Link from "next/link";
+
+import { prisma } from "@/lib/prisma";
+import { readCartFromCookies } from "@/lib/rental-cart-server";
+
+import { CartReview } from "./_components/CartReview";
+
+export const dynamic = "force-dynamic";
+
+export const metadata = { title: "Mon panier matériel" };
+
+export default async function CartPage() {
+  const cart = await readCartFromCookies();
+
+  // Charge les items du panier en bulk pour rendu
+  const ids = Array.from(new Set(cart.items.map((e) => e.itemId)));
+  const items = ids.length
+    ? await prisma.rentalItem.findMany({
+        where: { id: { in: ids } },
+        include: {
+          provider: { select: { id: true, name: true, isSystemD: true, commissionPct: true } },
+        },
+      })
+    : [];
+
+  const itemById = new Map(items.map((i) => [i.id, i]));
+  const lines = cart.items
+    .map((entry, idx) => {
+      const item = itemById.get(entry.itemId);
+      if (!item) return null;
+      return {
+        idx,
+        entry,
+        item: {
+          id: item.id,
+          name: item.name,
+          category: item.category,
+          imageUrl: item.imageUrl,
+          pricePerDay: item.pricePerDay.toString(),
+          deposit: item.deposit.toString(),
+          totalQty: item.totalQty,
+          provider: {
+            id: item.provider.id,
+            name: item.provider.name,
+            isSystemD: item.provider.isSystemD,
+          },
+        },
+      };
+    })
+    .filter((l): l is NonNullable<typeof l> => l !== null);
+
+  return (
+    <main className="mx-auto max-w-4xl px-6 py-10">
+      <header className="mb-6">
+        <Link href="/materiel" className="text-xs text-zinc-500 hover:text-zinc-900">
+          ← Continuer mes achats
+        </Link>
+        <h1 className="mt-1 text-3xl font-semibold text-zinc-900">Mon panier matériel</h1>
+        <p className="mt-1 text-sm text-zinc-600">
+          {lines.length === 0
+            ? "Votre panier est vide."
+            : `${lines.length} ligne${lines.length > 1 ? "s" : ""} de location.`}
+        </p>
+      </header>
+
+      {lines.length === 0 ? (
+        <div className="rounded-lg border border-dashed border-zinc-300 px-6 py-12 text-center">
+          <p className="text-sm text-zinc-600">Pas encore d&apos;item dans votre panier.</p>
+          <Link
+            href="/materiel"
+            className="mt-3 inline-block rounded-md bg-emerald-600 px-4 py-2 text-sm font-semibold text-white hover:bg-emerald-700"
+          >
+            Découvrir le matériel
+          </Link>
+        </div>
+      ) : (
+        <CartReview lines={lines} />
+      )}
+    </main>
+  );
+}