fix: code compliance audit and fix across all services

NestJS (6 services): implement @RequirePermission decorator with
SetMetadata+Reflector, register APP_GUARD globally, fix as assertions
to type guards, add explicit return types, fix import type for express,
fix /metrics implicit any, replace native Error with ApplicationError,
remove typeorm remnants, register LifecycleService.

teacher-bff: add logger, ApplicationError, GlobalErrorFilter, forward
real userId to downstream, log downstream failures, migrate health
controller to shared/health.

Go (2 services): interface to any, doc comments, CORS dev whitelist,
JWT secret fail-fast, push-gateway internal API auth, metrics and
readyz endpoints, remove dead code.

Python (2 services): lifespan return type, dev_mode to bool, data-ana
APIRouter, ai POST body model, ClickHouse async wrapping.

services/iam/src/main.ts

@@ -6,6 +6,7 @@ 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";
+import type { Request, Response } from "express";
 
 async function bootstrap(): Promise<void> {
   initTracer();
@@ -19,7 +20,7 @@ async function bootstrap(): Promise<void> {
 
   // 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) => {
+  app.getHttpAdapter().get("/metrics", async (_req: Request, res: Response) => {
     res.set("Content-Type", metricsRegistry.contentType);
     res.end(await metricsRegistry.metrics());
   });