feat(infra): p6 hardening - observability and deploy compose

- 5 NestJS services add /metrics endpoint via app.getHttpAdapter()
- prometheus.yml scales to 8 services with rule_files and alertmanager
- monitoring compose replaces blackbox with Loki+Promtail
- Grafana datasource adds Loki
- docker-compose.deploy.yml scales to 11 services
- deploy.env.example completes Neo4j/ES/ClickHouse/LLM vars
- teacher-bff adds health.controller
- CI removes continue-on-error on lint step
- teacher-portal lint script changed to eslint src

services/classes/src/main.ts

@@ -1,31 +1,39 @@
-import 'reflect-metadata';
-import { NestFactory } from '@nestjs/core';
-import { AppModule } from './app.module.js';
-import { GlobalErrorFilter } from './shared/errors/global-error.filter.js';
-import { initTracer, shutdownTracer } from './shared/observability/tracer.js';
-import { env } from './config/env.js';
-import { logger } from './shared/observability/logger.js';
+import "reflect-metadata";
+import { NestFactory } from "@nestjs/core";
+import { AppModule } from "./app.module.js";
+import { GlobalErrorFilter } from "./shared/errors/global-error.filter.js";
+import { initTracer, shutdownTracer } from "./shared/observability/tracer.js";
+import { env } from "./config/env.js";
+import { logger } from "./shared/observability/logger.js";
+import { metricsRegistry } from "./shared/observability/metrics.js";
 
 async function bootstrap(): Promise<void> {
   initTracer();
 
   const app = await NestFactory.create(AppModule, {
-    logger: ['log', 'error', 'warn'],
+    logger: ["log", "error", "warn"],
   });
 
   app.useGlobalFilters(new GlobalErrorFilter());
   app.enableShutdownHooks();
 
-  await app.listen(env.PORT);
-  logger.info({ port: env.PORT }, 'Classes service started');
+  // Prometheus 指标端点：不鉴权，供 Prometheus 抓取。
+  // 返回 register.metrics()（Promise<string>，含 Content-Type text/plain; version=0.0.4; charset=utf-8）。
+  app.getHttpAdapter().get("/metrics", async (req, res) => {
+    res.set("Content-Type", metricsRegistry.contentType);
+    res.end(await metricsRegistry.metrics());
+  });
 
-  process.on('SIGTERM', async () => {
+  await app.listen(env.PORT);
+  logger.info({ port: env.PORT }, "Classes service started");
+
+  process.on("SIGTERM", async () => {
     await app.close();
     await shutdownTracer();
   });
 }
 
 bootstrap().catch((err: unknown) => {
-  logger.error({ err }, 'Failed to start classes service');
+  logger.error({ err }, "Failed to start classes service");
   process.exit(1);
 });