refactor(admin): 替换硬编码 gray/white 为设计 token(login + layout)

- login/page.tsx、admin-layout.tsx 全部 Tailwind gray-* / bg-white / bg-black/50 映射至语义 token
- 深色面板(bg-gray-900/800 激活态、头像、登录按钮)映射 bg-dark-bg / bg-dark-bg-secondary,保持两模式深色
- 深色面板上的文字用 text-dark-text-primary(固定亮色),规避 text-white 在暗黑模式反色为暗的陷阱
- 遮罩 bg-black/50 → bg-overlay/50(独立 token,不随反色)
- 验证: type-check 0 / lint 0 / 产物 CSS 已含全部映射类

src/app/admin/login/page.tsx

@@ -30,32 +30,32 @@ export default function AdminLoginPage() {
   };
 
   return (
-    <div className="min-h-screen bg-gray-50 flex items-center justify-center p-4">
+    <div className="min-h-screen bg-bg-secondary flex items-center justify-center p-4">
       <div className="w-full max-w-md">
         <div className="text-center mb-8">
-          <h1 className="text-2xl font-bold text-gray-900">Novalon CMS</h1>
-          <p className="text-sm text-gray-500 mt-1">内容管理系统</p>
+          <h1 className="text-2xl font-bold text-text-primary">Novalon CMS</h1>
+          <p className="text-sm text-text-muted mt-1">内容管理系统</p>
         </div>
 
         <form
           onSubmit={handleSubmit}
-          className="bg-white rounded-xl shadow-sm border border-gray-200 p-6 space-y-5"
+          className="bg-bg-primary rounded-xl shadow-sm border border-border-primary p-6 space-y-5"
         >
           {error && (
-            <div className="bg-red-50 border border-red-200 text-red-700 rounded-lg px-4 py-3 text-sm">
+            <div className="bg-error-bg border border-border-secondary text-error rounded-lg px-4 py-3 text-sm">
               {error}
             </div>
           )}
 
           <div>
-            <label className="block text-sm font-medium text-gray-700 mb-1.5">
+            <label className="block text-sm font-medium text-text-secondary mb-1.5">
               用户名
             </label>
             <input
               type="text"
               value={username}
               onChange={(e) => setUsername(e.target.value)}
-              className="w-full px-3 py-2.5 border border-gray-300 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-gray-900 focus:border-transparent transition-shadow"
+              className="w-full px-3 py-2.5 border border-border-secondary rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-border-dark focus:border-transparent transition-shadow"
               placeholder="请输入用户名"
               required
               autoFocus
@@ -63,7 +63,7 @@ export default function AdminLoginPage() {
           </div>
 
           <div>
-            <label className="block text-sm font-medium text-gray-700 mb-1.5">
+            <label className="block text-sm font-medium text-text-secondary mb-1.5">
               密码
             </label>
             <div className="relative">
@@ -71,14 +71,14 @@ export default function AdminLoginPage() {
                 type={showPassword ? 'text' : 'password'}
                 value={password}
                 onChange={(e) => setPassword(e.target.value)}
-                className="w-full px-3 py-2.5 pr-10 border border-gray-300 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-gray-900 focus:border-transparent transition-shadow"
+                className="w-full px-3 py-2.5 pr-10 border border-border-secondary rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-border-dark focus:border-transparent transition-shadow"
                 placeholder="请输入密码"
                 required
               />
               <button
                 type="button"
                 onClick={() => setShowPassword(!showPassword)}
-                className="absolute right-3 top-1/2 -translate-y-1/2 text-gray-400 hover:text-gray-600"
+                className="absolute right-3 top-1/2 -translate-y-1/2 text-text-muted hover:text-text-tertiary"
               >
                 {showPassword ? <EyeOff className="w-4 h-4" /> : <Eye className="w-4 h-4" />}
               </button>
@@ -88,7 +88,7 @@ export default function AdminLoginPage() {
           <button
             type="submit"
             disabled={loading}
-            className="w-full flex items-center justify-center gap-2 bg-gray-900 text-white rounded-lg py-2.5 text-sm font-medium hover:bg-gray-800 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
+            className="w-full flex items-center justify-center gap-2 bg-dark-bg text-dark-text-primary rounded-lg py-2.5 text-sm font-medium hover:bg-dark-bg-secondary disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
           >
             {loading ? (
               <span className="animate-spin w-4 h-4 border-2 border-white border-t-transparent rounded-full" />