Add dark/light toggle to admin sidebar and topbar.

Reuse ThemeSwitcher with an admin variant (Sun/Moon) next to the staff profile and in the housekeeping header.

Co-authored-by: Cursor <[email protected]>

src/app/admin/layout.tsx

@@ -6,6 +6,7 @@ import type { ReactNode } from "react";
 import { AdminHubChrome } from "@/components/admin/admin-hub-chrome";
 import { AdminMobileWrapper } from "@/components/admin/admin-mobile-wrapper";
 import { AdminNavLink } from "@/components/admin/admin-nav-link";
+import { ThemeSwitcher } from "@/components/theme-switcher";
 import { requireStaff } from "@/lib/admin/guard";
 import { ADMIN_NAV_GROUPS } from "@/lib/admin-nav";
 import { prisma } from "@/lib/prisma";
@@ -73,6 +74,7 @@ async function Sidebar({
 						{t("rankLabel", { rank: staff.rank })}
 					</span>
 				</div>
+				<ThemeSwitcher variant="admin" />
 			</div>
 
 			<nav className="flex-1 overflow-y-auto px-3 py-4">
@@ -141,6 +143,7 @@ async function Topbar({
 				</span>
 			</div>
 			<div className="flex items-center gap-3">
+				<ThemeSwitcher variant="admin" />
 				<span className="text-xs text-[var(--admin-text-muted)]">
 					<strong className="text-[var(--admin-text)]">{staff.username}</strong>
 				</span>