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/settings/routes.py

@@ -15,7 +15,7 @@ from steward.core.settings import (
     get_stored_plugin_names, find_orphaned_plugins,
     to_smtp_cfg, to_webhook_cfg, to_ansible_cfg, to_plugins_cfg,
     to_oidc_cfg, to_ldap_cfg, to_thresholds_cfg, to_access_cfg, DEFAULTS, seal_source_tokens,
-    is_plugin_secret,
+    is_plugin_secret, NORM_FLOORS,
 )
 
 settings_bp = Blueprint("settings", __name__, url_prefix="/settings")
@@ -145,6 +145,8 @@ _THRESHOLD_FIELDS = [
     ("error_5xx_pct", "traefik.threshold.error_5xx_pct", True),
     ("error_4xx_pct", "traefik.threshold.error_4xx_pct", True),
     ("min_requests", "traefik.threshold.min_requests", False),
+    # Each normal's floor (#5742), named by its own setting key.
+    *[(f"norms.floor.{name}", f"norms.floor.{name}", True) for name in NORM_FLOORS],
 ]
 
 # Docker time-series retention windows (days). Read fresh by the cleanup task,
@@ -165,7 +167,8 @@ async def thresholds():
         settings = await get_all_settings(db)
     from steward.core.plugin_manager import _LOADED_PLUGINS
     return await render_template("settings/thresholds.html", settings=settings,
-                                 traefik_on="traefik" in _LOADED_PLUGINS)
+                                 traefik_on="traefik" in _LOADED_PLUGINS,
+                                 plugins_on=set(_LOADED_PLUGINS))
 
 
 @settings_bp.post("/thresholds/")