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/layout.tsx

@@ -16,10 +16,10 @@ const geistMono = Geist_Mono({
 
 export const metadata: Metadata = {
   title: {
-    template: "%s · 彩票后台",
-    default: "彩票后台",
+    template: "%s · Lottery Admin",
+    default: "Lottery Admin",
   },
-  description: "彩票后台管理端",
+  description: "Lottery administration console",
 };
 
 export default function RootLayout({