feat: initial commit — storefront, convex backend, and shared packages

Completes the first milestone of The Pet Loft ecommerce platform:
- apps/storefront: full customer-facing Next.js app with HeroUI (cart,
  checkout, orders, wishlist, product detail, shop, search, auth)
- convex/: serverless backend with schema, queries, mutations, actions,
  HTTP routes, Stripe/Shippo integrations, and co-located tests
- packages/types, packages/utils, packages/convex: shared workspace packages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/storefront/src/components/layout/header/mobile/MobileUtilityBar.tsx

@@ -0,0 +1,21 @@
+"use client";
+
+const PROMO_TEXT =
+  "☞ 10% off your first order ★ ☞ 5% off on all Re-orders over £30 ★ Free shipping on orders over £40 ★ ";
+
+export function MobileUtilityBar() {
+  return (
+    <div className="relative flex min-h-[2.5rem] w-full max-w-full items-center overflow-hidden border-b border-[#e8e8e8] bg-[#f5f5f5]">
+      <div className="absolute inset-0 flex items-center overflow-hidden" aria-hidden>
+        <div className="flex animate-marquee whitespace-nowrap">
+          <span className="inline-block pr-8 font-sans text-[10px] font-medium text-[#f2705a]">
+            {PROMO_TEXT}
+          </span>
+          <span className="inline-block pr-8 font-sans text-[10px] font-medium text-[#f2705a]">
+            {PROMO_TEXT}
+          </span>
+        </div>
+      </div>
+    </div>
+  );
+}