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/hosts/overview_widget.html

@@ -1,6 +1,8 @@
 {# hosts/overview_widget.html — the dashboard Hosts widget (#5251): a verdict,
    then one row per host, worst first, with its resources under one header.
-   Load is shown against the host's cores and graded per core. Reachability
+   Load is shown against the host's cores and graded per core. CPU, memory
+   and load within the host's own normal for the hour read healthy (#5742),
+   with what is usual on hover. Reachability
    and uptime belong to the Monitors widget, so they aren't repeated here. #}
 {% from "_macros.html" import status_dot %}
 {% if not rows %}
@@ -30,10 +32,12 @@
       {%- elif not a %}<span class="w-sub">no agent</span>{% endif %}
     </td>
     {% for v, kind in ((a.get('cpu_pct'), 'cpu'), (a.get('mem_used_pct'), 'mem'), (a.get('disk_root'), 'disk')) %}
-    <td style="{{ threshold_style(v, kind) if fresh and v is not none }}">{% if v is none %}—{% else %}{{ "%.0f"|format(v) }}%{% endif %}</td>
+    {% set g = (r.grades or {}).get(kind) or (none, none) %}
+    <td style="{{ grade_style(g[0]) }}"{% if g[1] %} title="{{ g[1]|capitalize }}"{% endif %}>{% if v is none %}—{% else %}{{ "%.0f"|format(v) }}%{% endif %}</td>
     {% endfor %}
-    <td style="{{ threshold_style(a.get('load_per_core'), 'load') if fresh and a.get('load_per_core') is not none }}"
-        title="{% if a.get('cores') %}Load over 1 minute on {{ a.cores }} cores: {{ a.load_per_core }}% of them busy or waiting{% endif %}">
+    {% set g = (r.grades or {}).get('load') or (none, none) %}
+    <td style="{{ grade_style(g[0]) }}"
+        title="{% if a.get('cores') %}Load over 1 minute on {{ a.cores }} cores: {{ a.load_per_core }}% of them busy or waiting{% endif %}{% if g[1] %}; {{ g[1] }}{% endif %}">
       {%- if a.get('load_1m') is none %}—{% elif a.get('cores') %}{{ "%.1f"|format(a.load_1m) }} / {{ a.cores }} cores{% else %}{{ "%.1f"|format(a.load_1m) }}{% endif -%}
     </td>
   </tr>