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/values-dev.yaml

@@ -0,0 +1,22 @@
+# parent-bff 开发环境
+
+replicaCount: 1
+
+image:
+  tag: dev
+
+configMap:
+  data:
+    NODE_ENV: development
+    LOG_LEVEL: debug
+    DEV_MODE: "true"
+    CORS_ORIGINS: http://localhost:4002
+
+hpa:
+  enabled: false
+
+podAntiAffinity:
+  enabled: false
+
+kafka:
+  enabled: false