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/configmap.yaml

@@ -0,0 +1,13 @@
+{{- if .Values.configMap.enabled }}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "parent-bff.name" . }}-config
+  namespace: {{ .Values.namespace }}
+  labels:
+    {{- include "parent-bff.labels" . | nindent 4 }}
+data:
+  {{- range $k, $v := .Values.configMap.data }}
+  {{ $k }}: {{ $v | quote }}
+  {{- end }}
+{{- end }}