feat(admin): 独立后台壳、站点分析与聊天监管，公开站拆出主题切换与访问埋点

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/admin/index.ts

@@ -13,3 +13,4 @@ export { default as AdminStatCard } from "./AdminStatCard";
 export { default as AdminIconButton } from "./AdminIconButton";
 export { default as AdminStatusChip, contentStatusChip } from "./AdminStatusChip";
 export type { AdminStatusTone } from "./AdminStatusChip";
+export { default as AdminShell } from "./AdminShell";