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/pages/NotFoundPage.tsx

@@ -5,7 +5,7 @@ export function NotFoundPage() {
     <div className="flex min-h-screen items-center justify-center bg-background-light p-6">
       <div className="card-std max-w-lg text-center">
         <p className="text-sm font-semibold uppercase tracking-wide text-primary">404</p>
-        <h1 className="mt-2 text-2xl font-bold text-slate-900">页面不存在</h1>
+        <h1 className="mt-2 text-2xl font-bold text-zinc-900">页面不存在</h1>
         <p className="mt-2 text-sm text-secondary">请检查地址，或返回工作台首页继续操作。</p>
         <div className="mt-5 flex justify-center">
           <Link className="btn-primary" to="/dashboard">