feat: route structure, providers, layouts, and placeholder pages

app/(order)/orders/page.tsx

@@ -0,0 +1,8 @@
+export default function OrderListPage() {
+  return (
+    <div className="container mx-auto py-8 px-4">
+      <h1 className="text-2xl font-bold">我的订单</h1>
+      <p className="mt-2 text-muted-foreground">查看和管理订单</p>
+    </div>
+  )
+}