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

services/parent-bff/test/unit/cache-key.builder.test.ts

@@ -0,0 +1,85 @@
+import { describe, it, expect } from "vitest";
+import { CacheKeys } from "../../src/shared/cache/cache-key.builder.js";
+
+describe("CacheKeys", () => {
+  describe("dashboard", () => {
+    it("应该为 dashboard 构建正确的 key", () => {
+      expect(CacheKeys.dashboard("parent-001")).toBe("dashboard:parent-001");
+    });
+  });
+
+  describe("children", () => {
+    it("应该为 children 构建正确的 key", () => {
+      expect(CacheKeys.children("parent-001")).toBe("children:parent-001");
+    });
+  });
+
+  describe("grades", () => {
+    it("应该为 grades 构建带分页的 key", () => {
+      expect(CacheKeys.grades("student-001", 1)).toBe("grades:student-001:1");
+      expect(CacheKeys.grades("student-002", 3)).toBe("grades:student-002:3");
+    });
+  });
+
+  describe("homework", () => {
+    it("应该为 homework 构建带 classId 的 key", () => {
+      expect(CacheKeys.homework("student-001", "class-001")).toBe(
+        "homework:student-001:class-001",
+      );
+    });
+  });
+
+  describe("exams", () => {
+    it("应该为 exams 构建带 classId 的 key", () => {
+      expect(CacheKeys.exams("student-001", "class-001")).toBe(
+        "exams:student-001:class-001",
+      );
+    });
+  });
+
+  describe("weakness", () => {
+    it("应该为 weakness 构建正确的 key", () => {
+      expect(CacheKeys.weakness("student-001")).toBe(
+        "analytics:weakness:student-001",
+      );
+    });
+  });
+
+  describe("trend", () => {
+    it("应该为 trend 构建带 range 的 key", () => {
+      expect(CacheKeys.trend("student-001", "7d")).toBe(
+        "analytics:trend:student-001:7d",
+      );
+    });
+  });
+
+  describe("notifications", () => {
+    it("应该为 notifications 构建带分页的 key", () => {
+      expect(CacheKeys.notifications("parent-001", 1)).toBe(
+        "notifications:parent-001:1",
+      );
+    });
+  });
+
+  describe("notificationPrefs", () => {
+    it("应该为 notificationPrefs 构建正确的 key", () => {
+      expect(CacheKeys.notificationPrefs("parent-001")).toBe(
+        "notification-prefs:parent-001",
+      );
+    });
+  });
+
+  describe("childBindings", () => {
+    it("应该为 childBindings 构建正确的 key", () => {
+      expect(CacheKeys.childBindings("parent-001")).toBe(
+        "child-bindings:parent-001",
+      );
+    });
+  });
+
+  it("不同 parentId 应该产生不同 key", () => {
+    expect(CacheKeys.dashboard("parent-001")).not.toBe(
+      CacheKeys.dashboard("parent-002"),
+    );
+  });
+});