feat(ui): alerts, monitors, hosts, schedules and maintenance lists put problems first, with since-times (#5210)

#5210 "Problems first, with since-time, across every list" (milestone 477),
first batch.

- Alerts: the Active list reads firing, no data, acknowledged, pending, the
  longest-running first, and re-polls itself. An acknowledged alert says how
  long it has been breaching (from the alert's events; acknowledging moves
  last_transition_at) and, apart from that, who acknowledged it and when.
  Rules show what each is doing now; disabled rules sort last. The current
  value reads the latest-value table (#5208) instead of plugin_metrics.
- Monitors: a down monitor says "Down 12m · connection refused" in the list.
- Hosts: sorted down, agent gone quiet, pending, healthy. The agent column
  shows "—" for a missing reading (was 0%) and a Stale badge with its age.
  agent_metrics_by_host is gone; the list reads agent_overview_by_host.
- Schedules: failing first (failed or interrupted run, or a firing that could
  not start one), then running, then the rest, paused last; status badge
  from the shared states.
- Maintenance windows: active (ending soonest), then upcoming (starting
  soonest), with expired folded away; each says when it ends/starts/ended.

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

steward/templates/ansible/schedules.html

@@ -1,5 +1,5 @@
 {% extends "base.html" %}
-{% from "_macros.html" import crumbs %}
+{% from "_macros.html" import crumbs, status_badge %}
 {% block title %}Ansible Schedules — Steward{% endblock %}
 {% block breadcrumb %}{{ crumbs([("Ansible", "/ansible/"), ("Schedules", "")]) }}{% endblock %}
 
@@ -39,9 +39,8 @@
     <td style="font-size:0.85rem;">{{ fmt_interval(s.interval_seconds) }}</td>
     <td style="font-size:0.82rem;">
       {% if row.last_run %}
-        {% set sc = {"queued":"var(--text-dim)","running":"var(--yellow)","success":"var(--green)","failed":"var(--red)","interrupted":"var(--orange)","cancelled":"var(--orange)"}.get(row.last_run.status.value, "var(--text-muted)") %}
-        <a href="/ansible/runs/{{ row.last_run.id }}" style="color:{{ sc }};font-weight:500;">{{ row.last_run.status.value }}</a>
-        <span style="color:var(--text-dim);">· {{ row.last_run.started_at.strftime("%m-%d %H:%M") }}</span>
+        <a href="/ansible/runs/{{ row.last_run.id }}" style="text-decoration:none;">{{ status_badge(row.last_run.status) }}</a>
+        <span style="color:var(--text-dim);">· {{ row.last_run.started_at|ago }}</span>
       {% endif %}
       {% if s.last_error %}
         {# With a run beside it, the last firing was skipped because that run was