Add postgres-mcp Helm chart

Wraps FreePeak/db-mcp-server: multi-database Postgres MCP driven by a
single JSON connection list, so new databases don't need a new Helm
release. Includes per-connection read_only/max_rows/query_timeout/
masking_rules guardrails and a PVC-backed audit log.

postgres-mcp/templates/service.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ .Release.Name }}
+  labels:
+    app.kubernetes.io/name: {{ .Chart.Name }}
+    app.kubernetes.io/instance: {{ .Release.Name }}
+spec:
+  type: ClusterIP
+  selector:
+    app: {{ .Release.Name }}
+  ports:
+    - name: http
+      port: {{ .Values.port }}
+      targetPort: http
+      protocol: TCP