Add VictoriaMetrics observability stack + sync catalog for monitoring test

- VM stack 10 charts: victoria-metrics-cluster/auth, victoria-logs-cluster,
  victoria-metrics-agent/alert, opentelemetry-collector, kube-state-metrics,
  prometheus-node-exporter, alertmanager, perses (JWT/OIDC, Infisical-ready)
- ArgoCD ApplicationSet (syncWave) + per-chart dip-values overlays
- doc/victoria-metrics-architecture.md, define-chart-resources updates
- includes pending working-tree changes (mlflow, kubeflow, apisix, CLAUDE.md)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

manifests/helm/victoria-metrics-alert/0.41.0/templates/alertmanager-configmap.yaml

@@ -0,0 +1,20 @@
+{{- $app := .Values.alertmanager }}
+{{- if and $app.enabled (empty $app.configMap) }}
+{{- $ctx := dict "helm" . "appKey" "alertmanager" }}
+{{- $fullname := include "vm.plain.fullname" $ctx }}
+{{- $ns := include "vm.namespace" $ctx }}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "alertmanager.config.name" $ctx }}
+  namespace: {{ $ns }}
+  labels: {{ include "vm.labels" $ctx | nindent 4 }}
+data:
+  alertmanager.yaml: |{{ toYaml $app.config | nindent 4 }}
+  {{- range $key, $value := $app.templates }}
+  {{ $key }}: |{{ $value | nindent 4 }}
+  {{- end }}
+  {{- with $app.webconfig }}
+  webconfig.yaml: |{{ toYaml . | nindent 4 }}
+  {{- end }}
+{{- end }}