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>

plugins/traefik/__init__.py

@@ -26,12 +26,12 @@ def setup(app: "Quart") -> None:
     # learned from the scrape-by-scrape figures only: before #5755 it was a
     # percentile of every response since Traefik started.
     from datetime import datetime, timezone
-    from steward.core.norms import learn_normal
-    from .routes import FLOOR_4XX, FLOOR_P95, STATE_WINDOW, min_requests
+    from steward.core.norms import floor_setting, learn_normal
+    from .routes import STATE_WINDOW, min_requests
     gate = ("request_rate",
             lambda: min_requests(app.config.get("THRESHOLDS", {})) / STATE_WINDOW.total_seconds())
-    learn_normal("traefik", "error_rate_4xx_pct", FLOOR_4XX, gate=gate)
-    learn_normal("traefik", "latency_p95_ms", FLOOR_P95, gate=gate,
+    learn_normal("traefik", "error_rate_4xx_pct", floor_setting(app, "router_4xx_pct"), gate=gate)
+    learn_normal("traefik", "latency_p95_ms", floor_setting(app, "router_p95_ms"), gate=gate,
                  since=datetime(2026, 10, 14, 18, 47, tzinfo=timezone.utc))