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/teacher-bff/src/shared/observability/logger.ts

@@ -0,0 +1,19 @@
+import pino from "pino";
+import { env } from "../../config/env.js";
+
+export const logger = pino({
+  level: env.LOG_LEVEL,
+  base: {
+    service: "teacher-bff",
+    version: "0.1.0",
+  },
+  transport:
+    env.NODE_ENV === "development"
+      ? {
+          target: "pino-pretty",
+          options: { colorize: true },
+        }
+      : undefined,
+});
+
+export type Logger = typeof logger;