feat: enhance DND nesting & promotion, isolated tags API, fix completion bounce UI, add Admin i18n switcher, refine typography & polish UX (v0.7.2)

src/app/admin/page.tsx

@@ -4,6 +4,7 @@ import Link from "next/link";
 import { useSession } from "next-auth/react";
 import { getDemoStore } from "@/lib/mockData";
 import { useI18n } from "@/lib/i18n";
+import { LanguageSelector } from "@/components/ui/LanguageSelector";
 
 interface AdminUser {
   id: string;
@@ -47,7 +48,7 @@ const INITIAL_DEMO_USERS: AdminUser[] = [
 
 export default function AdminPage() {
   const { data: session, status } = useSession();
-  const { t } = useI18n();
+  const { t, lang } = useI18n();
 
   const isDemo = status === "unauthenticated" || !session;
 
@@ -232,18 +233,19 @@ export default function AdminPage() {
           </div>
         </div>
 
-        <div style={{ display: "flex", gap: 8 }}>
+        <div style={{ display: "flex", alignItems: "center", gap: 8 }}>
+          <LanguageSelector />
           {isDemo ? (
             <Link href="/demo" className="btn btn-ghost btn-sm">
-              ← Back to Demo
+              ← {lang === "ko" ? "데모로 돌아가기" : lang === "ja" ? "デモに戻る" : "Back to Demo"}
             </Link>
           ) : (
             <button type="button" className="btn btn-ghost btn-sm" onClick={fetchAdminData}>
-              🔄 Refresh Data
+              🔄 {lang === "ko" ? "새로고침" : lang === "ja" ? "更新" : "Refresh"}
             </button>
           )}
           <Link href="/" className="btn btn-primary btn-sm">
-            🚀 Open Dashboard
+            🚀 {lang === "ko" ? "할 일 대시보드" : lang === "ja" ? "タスク一覧" : "Open Dashboard"}
           </Link>
         </div>
       </div>