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/MobileHeaderUserAction.tsx

@@ -0,0 +1,70 @@
+"use client";
+
+import { useConvexAuth } from "convex/react";
+import { UserButton } from "@clerk/nextjs";
+
+function OrdersIcon() {
+  return (
+    <svg
+      width="16"
+      height="16"
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth="2"
+      strokeLinecap="round"
+      strokeLinejoin="round"
+    >
+      <path d="M6 2 3 6v14a2 2 0 0 0 2 2h14a2 2 0 0 0 2-2V6l-3-4z" />
+      <line x1="3" y1="6" x2="21" y2="6" />
+      <path d="M16 10a4 4 0 0 1-8 0" />
+    </svg>
+  );
+}
+
+export function MobileHeaderUserAction() {
+  const { isLoading, isAuthenticated } = useConvexAuth();
+
+  if (isLoading || !isAuthenticated) {
+    return (
+      <a
+        href="/sign-in"
+        className="flex h-8 w-8 items-center justify-center rounded-full border border-[#d9e8e7] bg-[#f9fcfb]"
+      >
+        <svg
+          width="20"
+          height="20"
+          viewBox="0 0 24 24"
+          fill="none"
+          stroke="currentColor"
+          strokeWidth="1.5"
+          strokeLinecap="round"
+          strokeLinejoin="round"
+          className="text-[#3d5554]"
+        >
+          <path d="M20 21v-2a4 4 0 0 0-4-4H8a4 4 0 0 0-4 4v2" />
+          <circle cx="12" cy="7" r="4" />
+        </svg>
+      </a>
+    );
+  }
+
+  return (
+    <UserButton
+      afterSignOutUrl="/"
+      appearance={{
+        elements: {
+          avatarBox: "w-8 h-8",
+        },
+      }}
+    >
+      <UserButton.MenuItems>
+        <UserButton.Link
+          label="My Orders"
+          labelIcon={<OrdersIcon />}
+          href="/account/orders"
+        />
+      </UserButton.MenuItems>
+    </UserButton>
+  );
+}