Create a new monitor

curl --request POST \
  --url https://api.deeprails.com/monitor \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "name": "Customer Support Monitor",
  "description": "Monitor for customer support AI responses",
  "metrics": [
    "correctness",
    "completeness"
  ]
}'

{
  "success": true,
  "data": {
    "monitor_id": "mon-123e4567-e89b-12d3-a456-426614174000-1640995200",
    "user_id": "user-123",
    "name": "Customer Support Monitor",
    "description": "Monitor for customer support AI responses",
    "metrics": [
      "correctness",
      "completeness"
    ],
    "monitor_status": "active",
    "created_at": "2024-01-01T00:00:00Z",
    "updated_at": "2024-01-01T00:00:00Z"
  },
  "message": "Monitor created successfully"
}