feat(spark): deploy persistent Spark cluster with Web UI

- Add spark-cluster/base with Bitnami Spark chart 9.2.10 (master +
  2 workers), spark-events PVC (RWO/local-path), and Ingress resources
  for spark.nowchess.janis-eccarius.de (master UI) and
  spark-history.nowchess.janis-eccarius.de (history placeholder)
- Add spark-cluster/eu-central-1-prod overlay and ArgoCD Application
  (automated prune + selfHeal)
- Migrate all spark-analytics CronJobs and streaming Deployment from
  K8s-native mode (k8s://...) to Spark standalone (spark://spark-master:7077);
  drop kubernetes-specific --conf flags; add eventLog confs; mount
  spark-events PVC on all job pods

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

spark-cluster/base/charts/spark-9.2.10/spark/templates/init-configmap.yaml

@@ -0,0 +1,18 @@
+{{- /*
+Copyright Broadcom, Inc. All Rights Reserved.
+SPDX-License-Identifier: APACHE-2.0
+*/}}
+
+{{- if .Values.initScripts }}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ printf "%s-init-scripts" (include "common.names.fullname" .) }}
+  namespace: {{ include "common.names.namespace" . | quote }}
+  labels: {{- include "common.labels.standard" ( dict "customLabels" .Values.commonLabels "context" $ ) | nindent 4 }}
+  {{- if .Values.commonAnnotations }}
+  annotations: {{- include "common.tplvalues.render" ( dict "value" .Values.commonAnnotations "context" $ ) | nindent 4 }}
+  {{- end }}
+data:
+{{- include "common.tplvalues.render" ( dict "value" .Values.initScripts "context" $ ) | nindent 2 }}
+{{- end }}