Add customer accounts: login, signup, reset, activate, orders

- Storefront customer operations in graphql/customer.js and a server-safe
  services/shopify/customer.ts
- Session held in an httpOnly, sameSite=lax cookie set by the
  /api/account handlers; the access token never reaches client JS
- Pages: /account/login, /register, /recover, /reset/[id]/[token] and
  /activate/[id]/[token] for Shopify's emailed links
- /account renders order history as master-detail on one screen, since
  the Storefront API has no standalone order-by-id query for customers
- Header user icon: links to sign-in when signed out, otherwise a menu
  with name, email, order history, and sign out
- Login errors are collapsed and password recovery responds identically
  for known and unknown emails, so neither form enumerates accounts

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jWbNNJLksC1QG8z8845FX

app/account/login/page.tsx

@@ -0,0 +1,44 @@
+import Header from '@/components/shopify/header';
+import Footer from '@/components/shopify/footer';
+import AccountForm, { AccountFormLink } from '@/components/shopify/account-form';
+
+export const metadata = { title: 'Sign in — Shop' };
+
+export default function Page() {
+  return (
+    <>
+      <Header storeName="Shop" logoUrl="" />
+      <main className="max-w-screen-2xl mx-auto w-full px-8 py-16">
+        <AccountForm
+          title="Sign in"
+          fields={[
+            { name: 'email', label: 'Email', type: 'email', autoComplete: 'email' },
+            {
+              name: 'password',
+              label: 'Password',
+              type: 'password',
+              autoComplete: 'current-password',
+            },
+          ]}
+          submitLabel="Sign in"
+          endpoint="/api/account/login"
+          redirectTo="/account"
+          footer={
+            <>
+              <span>
+                New here?{' '}
+                <AccountFormLink href="/account/register">
+                  Create an account
+                </AccountFormLink>
+              </span>
+              <AccountFormLink href="/account/recover">
+                Forgot your password?
+              </AccountFormLink>
+            </>
+          }
+        />
+      </main>
+      <Footer storeName="Shop" copyright="© 2026 Shop. All rights reserved." />
+    </>
+  );
+}