(ui) Separate healthy and problematic dashboard runs

Split dashboard host cards into last successful backup and latest warning
or failed run so operators can quickly see whether a host is protected even
when recent activity produced an issue.

Also add queued and warning run counts to the dashboard summary metrics.

src/pobsync_backend/views.py

@@ -71,7 +71,9 @@ def dashboard(request):
             "enabled_schedules": ScheduleConfig.objects.filter(enabled=True).count(),
             "snapshots": SnapshotRecord.objects.count(),
             "runs": BackupRun.objects.count(),
+            "queued_runs": BackupRun.objects.filter(status=BackupRun.Status.QUEUED).count(),
             "running_runs": BackupRun.objects.filter(status=BackupRun.Status.RUNNING).count(),
+            "warning_runs": BackupRun.objects.filter(status=BackupRun.Status.WARNING).count(),
             "failed_runs": BackupRun.objects.filter(status=BackupRun.Status.FAILED).count(),
         },
     }