refactor(shared-ts,iam,core-edu,content,msg): remove outbox polling publisher

M8: Debezium CDC now handles outbox table to Kafka (ADR-032)

- Remove OutboxPublisher class from shared-ts

- Remove publisher from iam/core-edu/content/msg lifecycle and modules

- OutboxService retained for transactional outbox table writes

- Debezium monitors binlog and pushes to Kafka automatically

services/core-edu/src/main.ts

@@ -3,7 +3,6 @@ import { AppModule } from "./app.module.js";
 import { env } from "./config/env.js";
 import { connectKafka, disconnectKafka } from "./config/kafka.js";
 import { connectRedis, disconnectRedis } from "./config/redis.js";
-import { outboxPublisher } from "./shared/outbox/outbox.publisher.js";
 import { GlobalErrorFilter } from "./shared/errors/global-error.filter.js";
 import { initTracer, shutdownTracer } from "./shared/observability/tracer.js";
 import { logger } from "./shared/observability/logger.js";
@@ -24,9 +23,9 @@ async function bootstrap(): Promise<void> {
     res.end(await registry.metrics());
   });
 
-  // Connect Kafka producer/consumer before starting the outbox publisher.
-  // Non-blocking: if Kafka is unavailable, service still starts; outbox
-  // publisher will retry sends and messages stay pending until Kafka recovers.
+  // Connect Kafka producer/consumer.
+  // Non-blocking: if Kafka is unavailable, service still starts.
+  // v2.1（M8）：OutboxPublisher 轮询线程已移除，outbox 投递由 Debezium CDC 接管。
   void connectKafka();
 
   // Connect Redis for distributed lock (homework submission idempotency).
@@ -34,10 +33,6 @@ async function bootstrap(): Promise<void> {
   // operations will fall back to DB unique index for idempotency.
   void connectRedis();
 
-  // Start the transactional outbox publisher - polls pending messages
-  // and publishes them to Kafka topics defined in TOPIC_MAP.
-  await outboxPublisher.start();
-
   await app.listen(env.PORT);
 
   // 启动 gRPC server（9 Service / 40 RPC）
@@ -51,7 +46,6 @@ async function bootstrap(): Promise<void> {
   const shutdown = async (signal: string): Promise<void> => {
     logger.info({ signal }, "Shutting down gracefully...");
     await stopGrpcServer();
-    await outboxPublisher.stop();
     await disconnectRedis();
     await disconnectKafka();
     await shutdownTracer();