Add Helm chart scaffold with Chart.yaml, values.yaml, helpers, and all templates

Adds full Helm chart for GroomBook including migration job (pre-install/pre-upgrade hook), CNPG cluster (operator mode), DragonflyDB (integrated + operator modes), API/web deployments, services, and ingress templates.

Resolves GRO-89.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

charts/groombook/templates/serviceaccount.yaml

@@ -0,0 +1,13 @@
+{{- if .Values.serviceAccount.create }}
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: {{ include "groombook.serviceAccountName" . }}
+  labels:
+    {{- include "groombook.labels" . | nindent 4 }}
+  {{- with .Values.serviceAccount.annotations }}
+  annotations:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
+{{- end }}
+