GET /api/lines/spam-monitor

{
  "lines": [
    {
      "lineId": "abc123",
      "linePhone": "+19045551234",
      "lineType": "phone",
      "totalSentLast24h": 150,
      "failedLast24h": 3,
      "failureRate": 2.0,
      "consecutiveFailures": 0,
      "spamRisk": "low",
      "recommendation": "Line is healthy."
    }
  ]
}