fix(ui): [UI7-2] 统一全局 Design Tokens，移除冗余字体，修复异常色值引用

client/src/layouts/AuthLayout.tsx

@@ -2,7 +2,7 @@ import { Outlet } from "react-router-dom";
 
 export function AuthLayout() {
   return (
-    <div className="flex min-h-screen items-center justify-center bg-gradient-to-br from-primary-50 via-background-light to-slate-100 p-6">
+    <div className="flex min-h-screen items-center justify-center bg-gradient-to-br from-primary-50 via-background-light to-zinc-100 p-6">
       <div className="w-full max-w-md">
         <Outlet />
       </div>