🐛 fix(update): 修复 Windows 更新安装卡住并将安装包落到应用目录

- Windows 安装前预检当前安装目录写权限，避免脚本启动后主进程先退出
- 已下载更新补充打开安装目录入口，便于手动执行安装包
- 更新工作区优先改为当前应用运行目录，并补充回归测试与多语言文案

frontend/src/App.tsx

@@ -1709,6 +1709,7 @@ function App() {
       lastUpdateInfo,
       markUpdateProgressDismissed,
       muteLatestUpdate,
+      openDownloadedUpdateDirectory,
       setIsAboutOpen,
       showUpdateDownloadProgress,
       updateChannel,
@@ -4972,7 +4973,12 @@ function App() {
                 <Button key="check" icon={<CloudDownloadOutlined />} onClick={() => checkForUpdates(false)}>{t('app.about.action.check_updates')}</Button>,
                 <Button key="close" onClick={() => setIsAboutOpen(false)}>{t('common.close')}</Button>,
                 lastUpdateInfo?.hasUpdate && !isLatestUpdateDownloaded && !isBackgroundProgressForLatestUpdate ? (
-                    <Button key="download" type="primary" icon={<DownloadOutlined />} onClick={() => downloadUpdate(lastUpdateInfo, false)}>{t('app.about.action.download_update')}</Button>
+                <Button key="download" type="primary" icon={<DownloadOutlined />} onClick={() => downloadUpdate(lastUpdateInfo, false)}>{t('app.about.action.download_update')}</Button>
+                ) : null,
+                isLatestUpdateDownloaded ? (
+                    <Button key="open-install-directory" onClick={openDownloadedUpdateDirectory}>
+                        {t('app.about.action.open_install_directory')}
+                    </Button>
                 ) : null,
                 isLatestUpdateDownloaded ? (
                     <Button key="install-direct" type="primary" icon={<DownloadOutlined />} onClick={handleInstallFromProgress}>
@@ -6006,6 +6012,9 @@ function App() {
                   </Button>
               ] : (updateDownloadProgress.status === 'done' ? [
                   <Button key="close" onClick={hideUpdateDownloadProgress}>{t('common.close')}</Button>,
+                  <Button key="open-install-directory" onClick={openDownloadedUpdateDirectory}>
+                      {t('app.about.action.open_install_directory')}
+                  </Button>,
                   <Button key="install" type="primary" onClick={handleInstallFromProgress}>
                       {t('app.about.action.install_update')}
                   </Button>

frontend/src/hooks/useAppUpdateManager.test.tsx

@@ -183,4 +183,34 @@ describe('useAppUpdateManager', () => {
     expect(hook?.updateChannel).toBe('dev');
     expect(hook?.lastUpdateInfo?.channel).toBe('dev');
   });
+
+  it('opens the downloaded update directory when a package is already downloaded', async () => {
+    backendApp.CheckForUpdates.mockResolvedValue({
+      success: true,
+      data: {
+        hasUpdate: true,
+        currentVersion: '0.8.1',
+        latestVersion: '0.8.2',
+        downloaded: true,
+        assetSize: 1024,
+      },
+    });
+    backendApp.OpenDownloadedUpdateDirectory.mockResolvedValue({
+      success: true,
+      message: 'opened-install-directory',
+    });
+
+    renderHook();
+
+    await act(async () => {
+      await hook?.checkForUpdates(false);
+    });
+
+    await act(async () => {
+      await hook?.openDownloadedUpdateDirectory();
+    });
+
+    expect(backendApp.OpenDownloadedUpdateDirectory).toHaveBeenCalledTimes(1);
+    expect(messageApi.success).toHaveBeenCalledWith('opened-install-directory');
+  });
 });

frontend/src/hooks/useAppUpdateManager.ts

@@ -242,6 +242,20 @@ export const useAppUpdateManager = ({
     hideUpdateDownloadProgress();
   }, [hideUpdateDownloadProgress, lastUpdateInfo, lastUpdateKey, t, updateDownloadProgress.status]);
 
+  const openDownloadedUpdateDirectory = useCallback(async () => {
+    const backendApp = (window as any).go?.app?.App;
+    if (typeof backendApp?.OpenDownloadedUpdateDirectory !== 'function') {
+      void message.error(t('app.about.message.open_install_directory_failed_with_error', { error: t('common.unknown') }));
+      return;
+    }
+    const res = await backendApp.OpenDownloadedUpdateDirectory();
+    if (!res?.success) {
+      void message.error(t('app.about.message.open_install_directory_failed_with_error', { error: res?.message || t('common.unknown') }));
+      return;
+    }
+    void message.success(res?.message || t('app.about.message.install_directory_opened_manual_replace'));
+  }, [t]);
+
   const checkForUpdates = useCallback(async (silent: boolean) => {
     if (updateCheckInFlightRef.current) return;
     updateCheckInFlightRef.current = true;
@@ -523,6 +537,7 @@ export const useAppUpdateManager = ({
     lastUpdateInfo,
     markUpdateProgressDismissed,
     muteLatestUpdate,
+    openDownloadedUpdateDirectory,
     setIsAboutOpen,
     showUpdateDownloadProgress,
     updateChannel,