fix: 修复暗黑模式样式兼容性

- 在 tailwind.config.js 中启用 darkMode: 'class' 并扩展语义化颜色变量
- 将全项目硬编码颜色（bg-white、text-gray-*、border-gray-* 等）替换为语义化类名
- 修复 popup/index.html 硬编码浅色背景色
- 同步更新相关单元测试中的类名断言

pages/StorageCleaner/AutoRefreshToggle.tsx

@@ -8,8 +8,8 @@ interface AutoRefreshToggleProps {
 export default function AutoRefreshToggle({ autoRefresh, onChange }: AutoRefreshToggleProps) {
   const { t } = useLazyTranslation('storageCleaner');
   return (
-    <div className="mb-3 p-4 rounded-lg bg-white border border-gray-200 flex justify-between items-center shadow-sm transition-all hover:shadow-md">
-      <span className="text-sm font-bold text-gray-700 px-3">
+    <div className="mb-3 p-4 rounded-lg bg-background border border-border flex justify-between items-center shadow-sm transition-all hover:shadow-md">
+      <span className="text-sm font-bold text-foreground px-3">
         {t('storageCleaner:autoRefresh')}
       </span>
       <label className="relative inline-flex items-center cursor-pointer">
@@ -19,7 +19,7 @@ export default function AutoRefreshToggle({ autoRefresh, onChange }: AutoRefresh
           onChange={(e) => onChange(e.target.checked)}
           className="sr-only peer"
         />
-        <div className="w-9 h-5 bg-gray-200 peer-focus:outline-none peer-focus:ring-2 peer-focus:ring-amber-300 rounded-full peer peer-checked:after:translate-x-full peer-checked:after:border-white after:content-[''] after:absolute after:top-[2px] after:left-[2px] after:bg-white after:border-gray-300 after:border after:rounded-full after:h-4 after:w-4 after:transition-all peer-checked:bg-amber-500" />
+        <div className="w-9 h-5 bg-gray-200 peer-focus:outline-none peer-focus:ring-2 peer-focus:ring-amber-300 rounded-full peer peer-checked:after:translate-x-full peer-checked:after:border-white after:content-[''] after:absolute after:top-[2px] after:left-[2px] after:bg-background after:border-input after:border after:rounded-full after:h-4 after:w-4 after:transition-all peer-checked:bg-amber-500" />
       </label>
     </div>
   );