Remove AdminMenu from public site header

Hide admin interface completely from public site. Admins access /admin/login
directly. Cleaner separation between customer-facing UI and back office.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/components/Header.tsx

@@ -1,7 +1,6 @@
 import Link from 'next/link';
 import Image from 'next/image';
 import CartButton from './CartButton';
-import AdminMenu from './AdminMenu';
 import AccountMenu from './AccountMenu';
 import ThemeToggle from './ThemeToggle';
 import NavDropdown from './NavDropdown';
@@ -73,7 +72,6 @@ export default async function Header() {
           <div className="hidden md:block">
             <AccountMenu customer={customer ? { name: customer.name, email: customer.email } : null} />
           </div>
-          <AdminMenu />
           <ThemeToggle />
           <CartButton />
         </div>