feat: 添加账号异常状态 Webhook 通知功能

## 功能概述
- 新增账号禁用/异常状态的 Webhook 实时通知机制
- 支持 Claude OAuth、Claude Console、Gemini 三种平台的账号监控
- 提供完整的 Webhook 管理 API 和配置选项

## 主要变更

### 新增文件
- `src/utils/webhookNotifier.js`: Webhook 通知核心服务
- `src/routes/webhook.js`: Webhook 管理 API 路由

### 功能集成
- Claude OAuth 账号：unauthorized 状态 + token 刷新错误通知
- Claude Console 账号：blocked 状态通知
- Gemini 账号：token 刷新错误通知

### 配置支持
- 新增环境变量：WEBHOOK_ENABLED, WEBHOOK_URLS, WEBHOOK_TIMEOUT, WEBHOOK_RETRIES
- 支持多个 Webhook URL 并发通知
- 自动重试机制（指数退避）+ 超时保护

### 管理端点
- POST /admin/webhook/test: 测试连通性
- POST /admin/webhook/test-notification: 发送测试通知
- GET /admin/webhook/config: 查看配置信息

## 通知格式
```json
{
  "type": "account_anomaly",
  "data": {
    "accountId": "uuid",
    "accountName": "账号名称",
    "platform": "claude-oauth|claude-console|gemini",
    "status": "unauthorized|blocked|error",
    "errorCode": "CLAUDE_OAUTH_UNAUTHORIZED",
    "reason": "具体异常原因",
    "timestamp": "2025-01-13T10:30:00.000Z"
  }
}
```

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/routes/webhook.js

@@ -0,0 +1,120 @@
+const express = require('express')
+const router = express.Router()
+const logger = require('../utils/logger')
+const webhookNotifier = require('../utils/webhookNotifier')
+const { authenticateAdmin } = require('../middleware/auth')
+
+// 测试Webhook连通性
+router.post('/test', authenticateAdmin, async (req, res) => {
+  try {
+    const { url } = req.body
+
+    if (!url) {
+      return res.status(400).json({
+        error: 'Missing webhook URL',
+        message: 'Please provide a webhook URL to test'
+      })
+    }
+
+    // 验证URL格式
+    try {
+      new URL(url)
+    } catch (urlError) {
+      return res.status(400).json({
+        error: 'Invalid URL format',
+        message: 'Please provide a valid webhook URL'
+      })
+    }
+
+    logger.info(`🧪 Testing webhook URL: ${url}`)
+
+    const result = await webhookNotifier.testWebhook(url)
+
+    if (result.success) {
+      logger.info(`✅ Webhook test successful for: ${url}`)
+      res.json({
+        success: true,
+        message: 'Webhook test successful',
+        url: url
+      })
+    } else {
+      logger.warn(`❌ Webhook test failed for: ${url} - ${result.error}`)
+      res.status(400).json({
+        success: false,
+        message: 'Webhook test failed',
+        url: url,
+        error: result.error
+      })
+    }
+  } catch (error) {
+    logger.error('❌ Webhook test error:', error)
+    res.status(500).json({
+      error: 'Internal server error',
+      message: 'Failed to test webhook'
+    })
+  }
+})
+
+// 手动触发账号异常通知（用于测试）
+router.post('/test-notification', authenticateAdmin, async (req, res) => {
+  try {
+    const {
+      accountId = 'test-account-id',
+      accountName = 'Test Account',
+      platform = 'claude-oauth',
+      status = 'error',
+      errorCode = 'TEST_ERROR',
+      reason = 'Manual test notification'
+    } = req.body
+
+    logger.info(`🧪 Sending test notification for account: ${accountName}`)
+
+    await webhookNotifier.sendAccountAnomalyNotification({
+      accountId,
+      accountName,
+      platform,
+      status,
+      errorCode,
+      reason
+    })
+
+    logger.info(`✅ Test notification sent successfully`)
+
+    res.json({
+      success: true,
+      message: 'Test notification sent successfully',
+      data: {
+        accountId,
+        accountName,
+        platform,
+        status,
+        errorCode,
+        reason
+      }
+    })
+  } catch (error) {
+    logger.error('❌ Failed to send test notification:', error)
+    res.status(500).json({
+      error: 'Internal server error',
+      message: 'Failed to send test notification'
+    })
+  }
+})
+
+// 获取Webhook配置信息
+router.get('/config', authenticateAdmin, (req, res) => {
+  const config = require('../../config/config')
+
+  res.json({
+    success: true,
+    config: {
+      enabled: config.webhook?.enabled !== false,
+      urls: config.webhook?.urls || [],
+      timeout: config.webhook?.timeout || 10000,
+      retries: config.webhook?.retries || 3,
+      urlCount: (config.webhook?.urls || []).length
+    }
+  })
+})
+
+module.exports = router