fix(admin-web): 批量下载完成后直接触发浏览器另存为对话框

- 创建任务后自动轮询等待完成
- 完成后使用 <a download> 触发浏览器下载对话框
- 按钮显示打包进度
- 打包期间禁用按钮防止重复点击

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/admin-web/src/app/(dashboard)/contracts/page.tsx

@@ -139,9 +139,42 @@ export default function ContractsPage() {
     window.open(downloadUrl, '_blank');
   };
 
-  // 批量下载（创建下载任务）
+  // 批量下载状态
+  const [batchDownloading, setBatchDownloading] = useState(false);
+  const [batchProgress, setBatchProgress] = useState(0);
+
+  // 轮询任务状态直到完成
+  const pollTaskUntilComplete = async (taskNo: string): Promise<string | null> => {
+    const maxAttempts = 120; // 最多轮询2分钟
+    for (let i = 0; i < maxAttempts; i++) {
+      try {
+        const status = await contractService.getBatchDownloadStatus(taskNo);
+        setBatchProgress(status.progress);
+
+        if (status.status === 'COMPLETED' && status.resultFileUrl) {
+          return status.resultFileUrl;
+        } else if (status.status === 'FAILED') {
+          throw new Error('任务处理失败');
+        }
+
+        // 等待1秒后继续轮询
+        await new Promise(resolve => setTimeout(resolve, 1000));
+      } catch (error) {
+        console.error('查询任务状态失败:', error);
+        throw error;
+      }
+    }
+    throw new Error('任务处理超时');
+  };
+
+  // 批量下载（创建下载任务并等待完成后自动下载）
   const handleBatchDownload = async () => {
+    setBatchDownloading(true);
+    setBatchProgress(0);
+
     try {
+      toast.info('正在准备批量下载，请稍候...');
+
       const result = await contractService.createBatchDownload({
         filters: {
           signedAfter: filters.signedAfter || undefined,
@@ -151,15 +184,30 @@ export default function ContractsPage() {
         },
       });
 
-      toast.success(`批量下载任务已创建，任务号: ${result.taskNo}`);
+      // 轮询等待任务完成
+      const downloadUrl = await pollTaskUntilComplete(result.taskNo);
 
-      // 保存当前时间作为最后下载时间
-      const now = new Date().toISOString();
-      localStorage.setItem('contract_last_download_time', now);
-      setLastDownloadTime(now);
+      if (downloadUrl) {
+        // 创建隐藏的 a 标签触发浏览器下载（会弹出另存为对话框）
+        const link = document.createElement('a');
+        link.href = downloadUrl;
+        link.download = ''; // 设置 download 属性触发下载
+        document.body.appendChild(link);
+        link.click();
+        document.body.removeChild(link);
+        toast.success('请选择保存位置');
+
+        // 保存当前时间作为最后下载时间
+        const now = new Date().toISOString();
+        localStorage.setItem('contract_last_download_time', now);
+        setLastDownloadTime(now);
+      }
     } catch (error) {
-      console.error('创建批量下载任务失败:', error);
-      toast.error('创建批量下载任务失败');
+      console.error('批量下载失败:', error);
+      toast.error('批量下载失败，请重试');
+    } finally {
+      setBatchDownloading(false);
+      setBatchProgress(0);
     }
   };
 
@@ -170,7 +218,12 @@ export default function ContractsPage() {
       return;
     }
 
+    setBatchDownloading(true);
+    setBatchProgress(0);
+
     try {
+      toast.info('正在准备增量下载，请稍候...');
+
       const result = await contractService.createBatchDownload({
         filters: {
           signedAfter: lastDownloadTime,
@@ -179,15 +232,30 @@ export default function ContractsPage() {
         },
       });
 
-      toast.success(`增量下载任务已创建，任务号: ${result.taskNo}`);
+      // 轮询等待任务完成
+      const downloadUrl = await pollTaskUntilComplete(result.taskNo);
 
-      // 更新最后下载时间
-      const now = new Date().toISOString();
-      localStorage.setItem('contract_last_download_time', now);
-      setLastDownloadTime(now);
+      if (downloadUrl) {
+        // 创建隐藏的 a 标签触发浏览器下载（会弹出另存为对话框）
+        const link = document.createElement('a');
+        link.href = downloadUrl;
+        link.download = ''; // 设置 download 属性触发下载
+        document.body.appendChild(link);
+        link.click();
+        document.body.removeChild(link);
+        toast.success('请选择保存位置');
+
+        // 更新最后下载时间
+        const now = new Date().toISOString();
+        localStorage.setItem('contract_last_download_time', now);
+        setLastDownloadTime(now);
+      }
     } catch (error) {
-      console.error('创建增量下载任务失败:', error);
-      toast.error('创建增量下载任务失败');
+      console.error('增量下载失败:', error);
+      toast.error('增量下载失败，请重试');
+    } finally {
+      setBatchDownloading(false);
+      setBatchProgress(0);
     }
   };
 
@@ -295,11 +363,11 @@ export default function ContractsPage() {
           </div>
 
           <div className={styles.contracts__actions}>
-            <Button variant="primary" onClick={handleBatchDownload}>
-              批量下载 ZIP
+            <Button variant="primary" onClick={handleBatchDownload} disabled={batchDownloading}>
+              {batchDownloading ? `打包中 ${batchProgress}%...` : '批量下载 ZIP'}
             </Button>
             {lastDownloadTime && (
-              <Button variant="outline" onClick={handleIncrementalDownload}>
+              <Button variant="outline" onClick={handleIncrementalDownload} disabled={batchDownloading}>
                 增量下载（上次: {new Date(lastDownloadTime).toLocaleString('zh-CN')}）
               </Button>
             )}