feat: 添加多项功能和修复

功能新增:
- OSS 存储使用情况显示（文件页面）
- OSS 当日流量统计（阿里云云监控API）
- 分享页面路由修复（/s/xxx 格式支持）

Bug修复:
- 修复分享页面资源路径（相对路径改绝对路径）
- 修复分享码获取逻辑（支持路径格式）
- 修复OSS配额undefined显示问题
- 修复登录流程OSS配置检查
- 修复文件数为null时的显示问题

依赖更新:
- 添加 @alicloud/cms20190101 云监控SDK
- 添加 @alicloud/openapi-client

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

backend/server.js

@@ -6111,3 +6111,107 @@ app.listen(PORT, '0.0.0.0', () => {
   console.log(`外网访问地址: http://0.0.0.0:${PORT}`);
   console.log(`========================================\n`);
 });
+
+// ===== OSS 流量统计 API =====
+const Cms20190101 = require('@alicloud/cms20190101');
+const OpenApi = require('@alicloud/openapi-client');
+
+// 获取 OSS 当日流量统计（仅管理员或用户自己）
+app.get('/api/oss/traffic', authMiddleware, async (req, res) => {
+  try {
+    // 获取统一 OSS 配置
+    const ossConfig = SettingsDB.getUnifiedOssConfig();
+    if (!ossConfig) {
+      return res.status(400).json({
+        success: false,
+        message: 'OSS 未配置'
+      });
+    }
+
+    // 只支持阿里云
+    if (ossConfig.provider !== 'aliyun') {
+      return res.status(400).json({
+        success: false,
+        message: '流量统计仅支持阿里云 OSS'
+      });
+    }
+
+    // 创建云监控客户端
+    const config = new OpenApi.Config({
+      accessKeyId: ossConfig.access_key_id,
+      accessKeySecret: ossConfig.access_key_secret,
+    });
+    config.endpoint = 'metrics.cn-hangzhou.aliyuncs.com';
+    
+    const client = new Cms20190101.default(config);
+
+    // 获取今天的时间范围
+    const now = new Date();
+    const startOfDay = new Date(now.getFullYear(), now.getMonth(), now.getDate());
+    const startTime = startOfDay.toISOString();
+    const endTime = now.toISOString();
+
+    // 查询外网流出流量（下载）
+    const downloadReq = new Cms20190101.DescribeMetricLastRequest({
+      namespace: 'acs_oss_dashboard',
+      metricName: 'InternetSend',
+      dimensions: JSON.stringify([{ BucketName: ossConfig.bucket }]),
+      startTime: startTime,
+      endTime: endTime,
+      period: '86400', // 按天汇总
+    });
+
+    // 查询外网流入流量（上传）
+    const uploadReq = new Cms20190101.DescribeMetricLastRequest({
+      namespace: 'acs_oss_dashboard',
+      metricName: 'InternetRecv',
+      dimensions: JSON.stringify([{ BucketName: ossConfig.bucket }]),
+      startTime: startTime,
+      endTime: endTime,
+      period: '86400',
+    });
+
+    const [downloadRes, uploadRes] = await Promise.all([
+      client.describeMetricLast(downloadReq),
+      client.describeMetricLast(uploadReq)
+    ]);
+
+    // 解析结果
+    let downloadTraffic = 0;
+    let uploadTraffic = 0;
+
+    if (downloadRes.body?.datapoints) {
+      const datapoints = JSON.parse(downloadRes.body.datapoints);
+      if (datapoints.length > 0) {
+        downloadTraffic = datapoints.reduce((sum, dp) => sum + (dp.Value || dp.value || 0), 0);
+      }
+    }
+
+    if (uploadRes.body?.datapoints) {
+      const datapoints = JSON.parse(uploadRes.body.datapoints);
+      if (datapoints.length > 0) {
+        uploadTraffic = datapoints.reduce((sum, dp) => sum + (dp.Value || dp.value || 0), 0);
+      }
+    }
+
+    res.json({
+      success: true,
+      traffic: {
+        download: downloadTraffic,
+        downloadFormatted: formatFileSize(downloadTraffic),
+        upload: uploadTraffic,
+        uploadFormatted: formatFileSize(uploadTraffic),
+        total: downloadTraffic + uploadTraffic,
+        totalFormatted: formatFileSize(downloadTraffic + uploadTraffic),
+        date: startOfDay.toISOString().split('T')[0]
+      }
+    });
+
+  } catch (error) {
+    console.error('[OSS流量统计] 查询失败:', error);
+    res.status(500).json({
+      success: false,
+      message: '查询流量失败: ' + (error.message || '未知错误')
+    });
+  }
+});