0.31.1: make dashboard metrics honest

- Container card now compares compose-only counts across hosts: agents
  report compose_running in /agent/system (pre-0.31.1 agents fall back to
  the all-containers number); card retitled, ResourceBar stat labelled
  'Containers (all)'.
- Uptime is sampled every 5 min (background loop + opportunistic on read)
  and charted as daily averages instead of a once-a-day snapshot; no
  sample is written when no compose containers exist (was: fake 100%).
  Legacy daily entries in uptime.jsonl still count; file pruned at startup.
- Funnel stage 'monitored' is now per-stack and real: stacks with an
  enabled local auto-update policy (was: global webhook-exists toggle).
  Frontend label renamed to 'Auto-managed'.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -172,14 +172,16 @@ as intuitive as Dockge, as capable as Portainer for Compose workflows.
   (`bg`/`card`/`accent`) are remapped onto the tokens so all pages reskin
   consistently. Typeface: Schibsted Grotesk (bundled, offline-friendly).
 - **Stack Health funnel** — the dashboard centrepiece. Five stages
-  (`discovered → running → healthy → updated → monitored`) from
-  `GET /api/dashboard/funnel` (30 s server cache, `?refresh=true` to bust).
-  SVG waterfall with alternating gradient / diagonal-hatch bars, value chips
-  and hover conversion/drop-off tooltips.
-- **Summary widgets** from `GET /api/dashboard/summary`: containers-running
-  card with per-host breakdown and an "Insights" chip (healthy-rate %), a
-  30-day uptime line chart (daily samples appended to `DATA_DIR/uptime.jsonl`),
-  and an ops contribution grid from audit-log activity with the peak weekday.
+  (`discovered → running → healthy → updated → auto-managed`) from
+  `GET /api/dashboard/funnel` (30 s server cache, `?refresh=true` to bust;
+  the last stage — API key `monitored` — counts stacks with an enabled
+  auto-update policy). SVG waterfall with alternating gradient /
+  diagonal-hatch bars, value chips and hover conversion/drop-off tooltips.
+- **Summary widgets** from `GET /api/dashboard/summary`: compose-containers
+  card with per-host breakdown (agents report a compose-only count) and an
+  "Insights" chip (healthy-rate %), a 30-day uptime line chart (sampled every
+  5 min into `DATA_DIR/uptime.jsonl`, charted as daily averages), and an ops
+  contribution grid from audit-log activity with the peak weekday.
   A 30/7-day range selector slices both series client-side.
 - **Explore prompt bar** under the funnel: typed queries or `/running`,
   `/stopped`, `/attention` tags deep-link to the Stacks page, which now