feat(anomalies): a metric out of its normal is an anomaly to review (#5740)

#5740 "A metric that departs from its normal is recorded as an anomaly to
review, and is findable after it ends", milestone 513.

- Every minute each learned key's last 15 minutes is judged against its
  hour's normal: above the usual hold x1.25 and by the metric's floor opens
  an occurrence, which ends when the level comes back.
- metric_anomalies holds one row per item to review; a repeat while it
  still waits joins it as an occurrence (metric_anomaly_spans).
- An ended row nobody reviews within anomalies.review_days (14, Settings ->
  Thresholds) lapses; an ongoing one never does.
- Learning skips every hour an occurrence covers unless its anomaly was
  marked normal: no normal is learned without review.
- Alerts -> Anomalies lists those to review first, then the reviewed and
  lapsed under day dividers; marking is operator/admin and audited.
- The Overview widget and get_overview warn of open ones and count those
  to review; the host page shows its own; the weekly report lists the
  week's and the lapsed; MCP list_anomalies and review_anomaly.
- Reviewed and lapsed rows are pruned at data.retention_days, and kept
  in backups like alert history.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/hosts/routes.py

@@ -1,13 +1,13 @@
 from __future__ import annotations
 import asyncio
 import uuid
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 from quart import Blueprint, make_response, render_template, request, redirect, url_for, current_app, session
 from sqlalchemy import select
 from steward.ansible import executor, sources as ansible_src
 from steward.alerts import service as alert_svc
 from steward.auth.middleware import require_role
-from steward.core import renames
+from steward.core import anomalies as anom, renames
 from steward.core.audit import audit_request, log_audit
 from steward.models.ansible import AnsibleRun, AnsibleRunStatus
 from steward.models.hosts import Host
@@ -131,10 +131,14 @@ async def host_detail(host_id: str):
         linkable_targets = (await db.execute(
             select(AnsibleTarget).where(AnsibleTarget.host_id.is_(None))
             .order_by(AnsibleTarget.name))).scalars().all()
+        # The host's metric anomalies, its disks and interfaces included (#5740).
+        anomalies = await anom.views(db, await anom.list_anomalies(
+            db, source="host_agent", resource=host.name,
+            since=datetime.now(timezone.utc) - timedelta(days=30), limit=10), links=False)
 
     return await render_template(
         "hosts/detail.html",
-        host=host, monitors=monitors, uptime=uptime, alerts=alerts,
+        host=host, monitors=monitors, uptime=uptime, alerts=alerts, anomalies=anomalies,
         linked_target=linked_target, linkable_targets=linkable_targets,
         ansible_sources=_ansible_source_names(),
     )