feat(docker): Swarm task awareness — replaced tasks, service crash loops, last task error

Milestone 465 "Swarm task awareness". Fixes three defects from the live MCP
review #4973:
- #5008 "Swarm task history read as live state"
- #5009 "Crash-loop detection is blind to Swarm services"
- #5011 "Swarm task errors are not captured"

Agent and ingest (agent 1.8.0):
- A manager's agent now reports each service's newest tasks: slot, node,
  desired and current state, Swarm's Err/Message, exit code and time.
- They are stored in docker_swarm_services.tasks_json (migration
  docker_010_swarm_tasks).

Swarm view (pure):
- A task container is "replaced" when Swarm set its task's desired state off
  `running`. Without the task on record, a newer or running task in the same
  slot decides.
- Replaced containers are no longer replicas or crashes.
- Each service gets, from the task records:
  - failures_1h and failures_24h (failed or rejected tasks);
  - crash_looping (Settings → Thresholds count);
  - last_error, in Swarm's own words.

MCP:
- New findings: swarm_service_crash_looping (critical) and swarm_task_failed
  (warning, on a healthy service with a failure in 24h).
- Down and degraded findings name the last task error.
- list_swarm_services carries the failure fields.
- Container rows mark swarm_replaced and give a replaced task no problems.

Web:
- The containers page swarm cards and the Swarm topology page show crash
  loops, recent failures and the last task error.
- The dashboard widget flags a crash loop, and its "failed (24h)" count no
  longer counts a rolling update's killed task.

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

plugins/docker/templates/docker/_swarm_failures.html

@@ -0,0 +1,31 @@
+{#- One line on a swarm service's task failures, from Swarm's own task records
+    (agent ≥ 1.8.0): a crash loop or the failures of the last 24h, and how the
+    newest troubled task ended, in Swarm's words. Expects `s` with state,
+    crash_looping, failures_1h, failures_24h and last_error; `style` is
+    optional extra CSS for the wrapper. Renders nothing for a healthy service
+    with no recent failures. -#}
+{%- macro ago(sec) -%}
+  {%- if sec < 90 -%}{{ sec }}s ago
+  {%- elif sec < 5400 -%}{{ sec // 60 }}m ago
+  {%- elif sec < 172800 -%}{{ sec // 3600 }}h ago
+  {%- else -%}{{ sec // 86400 }}d ago{%- endif -%}
+{%- endmacro -%}
+{%- set e = s.last_error -%}
+{%- if s.crash_looping or s.failures_24h or (e and s.state != 'healthy') %}
+<div style="display:flex;flex-wrap:wrap;align-items:baseline;gap:0.2rem 0.6rem;font-size:0.78rem;color:var(--text-muted);{{ style or '' }}">
+  {% if s.crash_looping %}
+  <span style="color:var(--red);font-weight:600;">Crash-looping · {{ s.failures_1h }} tasks failed in the last hour</span>
+  {% elif s.failures_24h %}
+  <span style="color:var(--orange);">{{ s.failures_24h }} task{{ 's' if s.failures_24h != 1 }} failed in the last 24h</span>
+  {% endif %}
+  {% if e %}
+  <span title="How Swarm recorded the end of this service's newest failed task">
+    Last task {{ e.state }}:
+    <span style="color:var(--text);font-family:ui-monospace,monospace;overflow-wrap:anywhere;">{{ e.error or e.message or e.state }}</span>
+    {%- if e.exit_code %} · exit {{ e.exit_code }}{% endif %}
+    {%- if e.node %} · {{ e.node }}{% endif %}
+    {%- if e.age_s is not none %} · {{ ago(e.age_s) }}{% endif %}
+  </span>
+  {% endif %}
+</div>
+{%- endif %}

plugins/docker/templates/docker/rows.html

@@ -26,9 +26,10 @@
   </div>
 </div>
 
-{# ── Swarm services: collapsed per-service, each replica labelled with its host.
-   Ghost replicas (tasks on nodes with no Steward agent) come from the managers'
-   placement data so the picture is cluster-complete. ──────────────────────── #}
+{# ── Swarm services: collapsed per-service, each current replica labelled with
+   its host (tasks Swarm replaced are left out). Ghost replicas (tasks on nodes
+   with no Steward agent) come from the managers' placement data so the picture
+   is cluster-complete. A failing service names Swarm's last task error. ───── #}
 {% if swarm_services %}
 <div class="card-flush" style="margin-bottom:1.5rem;">
   <div style="display:flex;align-items:baseline;gap:0.6rem;padding:0.5rem 0.75rem;border-bottom:1px solid var(--border);">
@@ -46,6 +47,7 @@
           {{ s.running }}/{{ s.desired }} running
         </span>
       </div>
+      {% with style="padding-left:1.1rem;margin-bottom:0.35rem;" %}{% include "docker/_swarm_failures.html" %}{% endwith %}
       <div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(210px,1fr));gap:0.4rem;padding-left:1.1rem;">
         {% for r in s.replicas %}
         {% if r.ghost %}

plugins/docker/templates/docker/swarm.html

@@ -22,7 +22,7 @@
     <table class="table">
       <thead>
         <tr>
-          <th>Service</th><th>Mode</th><th>Replicas</th><th>Image</th><th>Placement</th>
+          <th>Service</th><th>Mode</th><th>Replicas</th><th>Image</th><th>Placement</th><th>Task failures</th>
         </tr>
       </thead>
       <tbody>
@@ -39,9 +39,14 @@
           <td style="font-size:0.78rem;color:var(--text-muted);">
             {% for p in s.placement %}{{ p.node }} ({{ p.running }}){% if not loop.last %}, {% endif %}{% else %}—{% endfor %}
           </td>
+          <td style="max-width:360px;">
+            {% include "docker/_swarm_failures.html" %}
+            {%- if not s.tasks_known %}<span style="font-size:0.78rem;color:var(--text-dim);" title="The reporting manager's agent predates task reporting (1.8.0); update it to see task failures.">—</span>
+            {%- elif not (s.crash_looping or s.failures_24h or (s.last_error and s.state != 'healthy')) %}<span style="font-size:0.78rem;color:var(--text-dim);">none in 24h</span>{% endif %}
+          </td>
         </tr>
         {% else %}
-        <tr><td colspan="5" style="color:var(--text-muted);font-size:0.85rem;text-align:center;padding:1.5rem;">No services in this swarm.</td></tr>
+        <tr><td colspan="6" style="color:var(--text-muted);font-size:0.85rem;text-align:center;padding:1.5rem;">No services in this swarm.</td></tr>
         {% endfor %}
       </tbody>
     </table>

plugins/docker/templates/docker/widget.html

@@ -8,7 +8,7 @@
     <span style="font-size:1.4rem;font-weight:700;line-height:1;color:var(--green);">{{ running_count }}</span>
     <span style="font-size:0.78rem;color:var(--text-muted);margin-left:0.25rem;">running</span>
   </div>
-  <div title="Distinct containers with a die or OOM event in the last 24h">
+  <div title="Containers that died or were OOM-killed in the last 24h, plus swarm tasks that failed (a task Swarm replaced is not a failure)">
     <span style="font-size:1.4rem;font-weight:700;line-height:1;color:{% if failed_24h %}var(--red){% else %}var(--text-muted){% endif %};">{{ failed_24h }}</span>
     <span style="font-size:0.78rem;color:var(--text-muted);margin-left:0.25rem;">failed (24h)</span>
   </div>
@@ -24,6 +24,7 @@
     <div style="display:flex;align-items:center;gap:0.4rem;font-size:0.82rem;">
       <span class="dot {% if s.state == 'healthy' %}dot-up{% elif s.state == 'degraded' %}dot-warn{% else %}dot-down{% endif %}"></span>
       <span style="font-weight:500;min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;">{{ s.name }}</span>
+      {% if s.crash_looping %}<span style="color:var(--red);font-size:0.7rem;font-weight:600;flex-shrink:0;" title="{{ s.failures_1h }} tasks failed in the last hour{% if s.last_error %}: {{ s.last_error.error or s.last_error.message or s.last_error.state }}{% endif %}">crash-looping</span>{% endif %}
       <span style="color:var(--text-muted);font-family:ui-monospace,monospace;font-size:0.74rem;margin-left:auto;flex-shrink:0;">{{ s.running }}/{{ s.desired }}</span>
     </div>
     <div style="display:flex;flex-wrap:wrap;gap:0.25rem;margin:0.2rem 0 0 1rem;">