feat: add n8n Helm chart for Kubernetes on Raspberry Pi (ARM64)

- n8nio/n8n 2.19.2 (multi-arch, linux/arm64 ready)
- Single-container deployment with persistent storage
- SQLite default / PostgreSQL option
- Basic auth, encryption key via Secret
- Ingress, HPA, PDB, NetworkPolicy support
- Gitea CI: weekly auto-update + release workflow

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

templates/pvc.yaml

@@ -0,0 +1,21 @@
+{{- if and .Values.persistence.enabled (not (.Values.persistence.existingClaim)) -}}
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: {{ include "n8n.fullname" . }}
+  labels:
+    {{- include "n8n.labels" . | nindent 4 }}
+  {{- with .Values.persistence.annotations }}
+  annotations:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
+spec:
+  accessModes:
+    - {{ .Values.persistence.accessMode }}
+  resources:
+    requests:
+      storage: {{ .Values.persistence.size }}
+  {{- if .Values.persistence.storageClass }}
+  storageClassName: {{ .Values.persistence.storageClass }}
+  {{- end }}
+{{- end }}