feat(docker): the service and container pages say each fact once (#5310)

Service page:
- The header carries the verdict, mode, stack, image and when it was reported.
  'In trouble since' shows only while the service is in trouble; once recovered,
  'Last failed X ago · its logs'.
- The failure card shows only while the service is down, degraded or crash-looping.
- The tile strip and the kv card are gone.
- One Tasks table: running tasks first with CPU, memory and since when, then
  Swarm's record. The node is named as its Steward host throughout, and
  'N failed in 24h' sits in the caption.

Container page:
- Same shape: header verdict, a 'Last exit' card only while it is stopped
  after a failing exit, set-up and I/O in one kv card, and lifecycle as a table.
- A swarm task's breadcrumb goes through its service.

Both pages:
- Resource history is the one fragment (_usage_history.html): now and peak in
  cores and bytes, drawn with a floor of 1 core / 1 GiB (sparkline_svg floor=),
  so idle noise draws flat.
- The container page's old % sparklines, its private _sparkline and the unused
  bucket()/container_history() helpers are removed.

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

steward/static/steward.css

@@ -213,7 +213,7 @@ strong, b, th { font-weight: 500; }
 .section-count { margin-bottom: 0.6rem; }
 .section-count > span:first-child { margin-left: 0.25rem; }
 /* A service's resource history: CPU and memory side by side, each a figure
-   over a line that spans its half (docker/_service_history.html). */
+   over a line that spans its half (docker/_usage_history.html). */
 .history-pair { display: grid; grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr)); gap: 1.25rem; }
 .history-pair .spark { color: var(--blue); margin-top: 0.4rem; }
 /* The Swarm page (#5303): one card per node, two or three a row on a wide