Fix theme consistency, i18n completeness, CSS variable naming, and hardcoded strings

src/app/admin/layout.tsx

@@ -163,10 +163,10 @@ async function Topbar({ staff }: { staff: { id: number; username: string; rank:
   const t = await getTranslations("pages.admin.nav");
 
   return (
-    <header className="flex items-center justify-between gap-4 bg-[var(--color-surface)] border border-[var(--border)] rounded-2xl px-5 py-3 mb-5 shadow-card">
+    <header className="flex items-center justify-between gap-4 bg-[var(--color-surface)] border border-[var(--border-subtle)] rounded-2xl px-5 py-3 mb-5 shadow-card">
       <div className="flex items-center gap-3">
         <h2 className="m-0 text-base font-extrabold text-[var(--color-text)]">{t("housekeeping")}</h2>
-        <span className="hidden sm:inline-block w-px h-5 bg-[var(--border)]" />
+        <span className="hidden sm:inline-block w-px h-5 bg-[var(--border-subtle)]" />
         <span className="hidden sm:inline text-xs text-[var(--color-text-muted)]">
           {t("hotelManagementPanel")}
         </span>