refactor(admin): tokenize 语义色并补暗黑模式变量覆盖

将 admin 8 文件 ~50 处 raw red/green/yellow/amber/blue 类替换为语义 token
（error/success/warning/info），使其错误/成功/警告框在暗黑模式正确反色。

- tailwind.config.js: error 补 text 子键（原缺，text-error 暗黑底仅 3.3:1 不达 AA）
- globals.css: 新增 --color-error-text；html[data-theme='dark'] 补四语义色的
  *-bg（深色底）与 *-text（浅色，暗底达 AA）覆盖，原暗黑块完全漏掉这些变量
- 映射纪律：语义框 bg-<c>-bg border border-border-secondary text-<c>-text；
  危险按钮 bg-error/bg-success hover:bg-*-hover text-white；字段校验 border-error

验证：type-check 0 errors；lint 0 errors；单测 1624 passed；视觉回归 22 passed；
Playwright 实测 8 变量 light/dark 翻转 + 真实登录错误框背景反色确认。

Co-Authored-By: 阿睿 <workbuddy@tencent.com>

src/app/admin/users/page.tsx

@@ -45,10 +45,10 @@ const ROLE_LABELS: Record<string, string> = {
 };
 
 const ROLE_COLORS: Record<string, string> = {
-  super_admin: 'bg-red-100 text-red-700',
-  content_admin: 'bg-blue-100 text-blue-700',
-  content_editor: 'bg-green-100 text-green-700',
-  reviewer: 'bg-amber-100 text-amber-700',
+  super_admin: 'bg-error-bg text-error-text',
+  content_admin: 'bg-info-bg text-info-text',
+  content_editor: 'bg-success-bg text-success-text',
+  reviewer: 'bg-warning-bg text-warning-text',
   readonly: 'bg-bg-hover text-text-secondary',
 };
 
@@ -266,7 +266,7 @@ export default function UsersPage() {
       </div>
 
       {error && (
-        <div className="p-4 bg-red-50 border border-red-200 rounded-lg text-sm text-red-600">
+        <div className="p-4 bg-error-bg border border-border-secondary rounded-lg text-sm text-error-text">
           {error}
         </div>
       )}
@@ -344,8 +344,8 @@ export default function UsersPage() {
                       <span
                         className={`inline-flex items-center px-2 py-0.5 rounded-full text-xs font-medium ${
                           u.status === 1
-                            ? 'bg-green-100 text-green-700'
-                            : 'bg-red-100 text-red-700'
+                            ? 'bg-success-bg text-success-text'
+                            : 'bg-error-bg text-error-text'
                         }`}
                       >
                         {u.status === 1 ? '启用' : '禁用'}
@@ -368,7 +368,7 @@ export default function UsersPage() {
                         </button>
                         <button
                           onClick={() => { setPendingDeleteId(u.id); setDeleteDialogOpen(true); }}
-                          className="p-1.5 rounded hover:bg-red-50 text-text-muted hover:text-red-600"
+                          className="p-1.5 rounded hover:bg-error-bg text-text-muted hover:text-error-text"
                           title="删除"
                         >
                           <Trash2 className="w-4 h-4" />
@@ -529,7 +529,7 @@ export default function UsersPage() {
           </AlertDialogHeader>
           <AlertDialogFooter>
             <AlertDialogCancel>取消</AlertDialogCancel>
-            <AlertDialogAction onClick={handleDelete} className="bg-red-600 hover:bg-red-700">
+            <AlertDialogAction onClick={handleDelete} className="bg-error hover:bg-error-hover">
               确认删除
             </AlertDialogAction>
           </AlertDialogFooter>