feat(norms): hosts, containers and monitor response times are graded against their own normal (#5742)

Host CPU, memory and load per core, container CPU and memory, and every
monitor's response time learn a normal per hour (milestone 513, System 182).
A reading past its fixed cutoff but within its normal reads healthy and says
what is usual at this hour; one well out of it keeps its grade and is a
metric anomaly. Disk, a monitor down and an agent offline keep their cutoffs.

- Each normal's floor, the smallest departure that counts, is a setting:
  Settings -> Thresholds -> Normals (norms.floor.*). Defaults: host CPU 10
  points, host memory 5, load per core 10, container CPU 10 points of one
  core, container memory 5, monitor response 100 ms; Traefik's 2-point 4xx
  and 50 ms p95 floors move there from constants. learn_normal takes a
  floor function (floor_setting) read at each pass.
- learn_normal(parts=False): a host learns, its cores don't.
- Ingest records load_pct (load_1m / cores x 100), the figure pages grade.
- Shared grading: anomalies.against / graded, worst_reading(normals=),
  hosts' host_grades, docker usage(thresholds=, norms=), monitors'
  latency_grade. Applied to host vitals, the Hosts widget, MCP overview,
  Docker usage, and the monitor list, widget and page.
- The monitor and container pages list their anomalies.

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

steward/templates/monitors/rows.html

@@ -51,7 +51,7 @@
     {% if d.state in ('down', 'paused', 'pending') %}{{ status_badge(d.state) }}
     {% elif latest.response_ms is not none %}
       {% if d.spark %}<span class="mon-spark" title="Response time over the last 30 checks">{{ d.spark|safe }}</span>{% endif %}
-      <span class="tone-{{ status_class(latest.response_ms, 'latency') }}">{{ "%.0f"|format(latest.response_ms) }} ms</span>
+      <span class="tone-{{ d.latency }}"{% if d.latency_usual %} title="{{ d.latency_usual|capitalize }}"{% endif %}>{{ "%.0f"|format(latest.response_ms) }} ms</span>
     {% elif m.type == 'dns' and latest.resolved_ip %}<span class="tone-ok">{{ latest.resolved_ip }}</span>
     {% else %}{{ status_badge('up') }}{% endif %}
   </div>