feat: add agentmon services section to infrastructure page

Label all agentmon docker-compose services with agentmon.monitor=true
and agentmon.group=agentmon so the swarm-monitor picks them up.
Adds Group field to ServiceSnapshot, probes /healthz for api/web roles,
and renders a separate "Agentmon" section below Swarm Services on the
Infrastructure page with new api and worker card renderers.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/monitor/swarm/collector.go

@@ -87,6 +87,7 @@ func collectOne(ctx context.Context, c dockerContainer, dockerClient, httpClient
 	name := containerName(c)
 	snap := ServiceSnapshot{
 		Name:           name,
+		Group:          c.Labels["agentmon.group"],
 		Role:           c.Labels["agentmon.role"],
 		ContainerState: c.State,
 		HealthState:    "none",
@@ -121,6 +122,10 @@ func collectOne(ctx context.Context, c dockerContainer, dockerClient, httpClient
 		collectHTTPProbe(ctx, &snap, httpClient, "http://localhost:"+port+"/")
 	case "mcp":
 		collectPortProbe(&snap, port)
+	case "api", "web":
+		if port != "" {
+			collectHTTPProbe(ctx, &snap, httpClient, "http://localhost:"+port+"/healthz")
+		}
 	}
 
 	snap.Status = deriveStatus(snap)