refactor: 更新管理端页面元数据，统一国际化支持，移除冗余代码

src/app/admin/(shell)/page.tsx

@@ -1,10 +1,9 @@
 import { ModuleScaffold } from "@/components/admin/module-scaffold";
 import { DashboardConsole } from "@/modules/dashboard/dashboard-console";
+import { buildPageMetadata } from "@/lib/page-metadata";
 import type { Metadata } from "next";
 
-export const metadata: Metadata = {
-  title: "仪表盘",
-};
+export const metadata: Metadata = buildPageMetadata("dashboard", "title");
 
 export default function AdminDashboardPage() {
   return (