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.
