fix: remove @tauri-apps/api/os import and use local UA/platform detection for mac class

src/main.tsx

@@ -4,16 +4,18 @@ import App from './App'
 import './index.css'
 // 导入 Tauri API（自动绑定到 window.api）
 import './lib/tauri-api'
-import { platform as osPlatform } from '@tauri-apps/api/os'
 
 // 根据平台添加 body class，便于平台特定样式
-osPlatform().then((p) => {
-  if (p === 'darwin') {
+try {
+  const ua = navigator.userAgent || ''
+  const plat = (navigator.platform || '').toLowerCase()
+  const isMac = /mac/i.test(ua) || plat.includes('mac')
+  if (isMac) {
     document.body.classList.add('is-mac')
   }
-}).catch(() => {
+} catch {
   // 忽略平台检测失败
-})
+}
 
 ReactDOM.createRoot(document.getElementById('root')!).render(
   <React.StrictMode>