feat: initialize parent-bff service with full core features

add complete parent-bff implementation including:
- GraphQL endpoint with depth/cost validation
- ChildGuard越权校验 with redis cache and singleflight
- parallel orchestration with partial failure fallback
- three-level cache fallback strategy (Redis + LRU + downstream)
- Kafka consumer for cache invalidation and notification push
- opossum circuit breaker for downstream services
- Prometheus metrics and SLO alerts
- Helm chart for k8s deployment with multi-environment configs
- Grafana dashboard for observability
- complete unit and integration tests

infra/k8s/helm/parent-bff/templates/service.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ include "parent-bff.name" . }}
+  namespace: {{ .Values.namespace }}
+  labels:
+    {{- include "parent-bff.labels" . | nindent 4 }}
+spec:
+  type: {{ .Values.service.type }}
+  selector:
+    {{- include "parent-bff.selectorLabels" . | nindent 4 }}
+  ports:
+    - name: http
+      port: {{ .Values.service.port }}
+      targetPort: http
+      protocol: TCP