feat(core-edu): 完整实现 core-edu 教学核心服务

包含 classes/exams/homework/grades/attendance/scheduling 域、outbox、iam-consumer、redis 配置等完整实现

services/core-edu/src/shared/outbox/event-builder.ts

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+import { randomUUID } from "node:crypto";
+
+/**
+ * Outbox 事件构建器
+ *
+ * 所有事件 payload 必须包含（events.proto 仲裁 §2.1）：
+ *   - event_id: UUID（幂等消费）
+ *   - occurred_at: 业务时间戳（ms epoch）
+ *   - schema_version: 默认 "v1"
+ *   - metadata: { traceId, userId }
+ */
+
+export interface EventMetadata {
+  schema_version: string;
+  trace_id: string;
+  user_id: string;
+}
+
+export interface OutboxEvent<T = Record<string, unknown>> {
+  event_id: string;
+  aggregate_id: string;
+  event_type: string;
+  occurred_at: number;
+  payload: T;
+  metadata: EventMetadata;
+}
+
+export interface BuildEventInput {
+  aggregateId: string;
+  eventType: string;
+  payload: Record<string, unknown>;
+  userId?: string;
+  traceId?: string;
+  schemaVersion?: string;
+}
+
+/**
+ * 构建标准 Outbox 事件（含 event_id / occurred_at / schema_version / metadata）。
+ * 返回的对象可直接 JSON.stringify 作为 outbox.payload 存储。
+ */
+export function buildEvent(input: BuildEventInput): OutboxEvent {
+  return {
+    event_id: randomUUID(),
+    aggregate_id: input.aggregateId,
+    event_type: input.eventType,
+    occurred_at: Date.now(),
+    payload: input.payload,
+    metadata: {
+      schema_version: input.schemaVersion ?? "v1",
+      trace_id: input.traceId ?? "unknown",
+      user_id: input.userId ?? "system",
+    },
+  };
+}
+
+/**
+ * 将 OutboxEvent 序列化为 JSON 字符串（用于 outbox.payload 列）。
+ */
+export function serializeEvent(event: OutboxEvent): string {
+  return JSON.stringify(event);
+}