[Datadog] Seasonality-Aware Anomaly Detection

This query uses Datadog’s proprietary anomalies() function, which applies a seasonal trend decomposition. Recreating this in Elastic requires configuring a specific Machine Learning (ML) job, as standard Elastic alerts don't handle triple-exponential smoothing natively within a simple query.

```json
{
"name": "Seasonal Anomaly: Checkout Latency",
"type": "query alert",
"query": "avg(last_4h):anomalies(avg:ecommerce.checkout.latency{env:prod}, 'agile', 2, direction='both', alert_window='last_15m', interval=60, count_default_zero='true') >= 1",
"message": "Checkout latency is deviating from historical weekly patterns. @ops-team",
"options": {
"thresholds": { "critical": 1 }
}
}
```