- main: add base context via signal.NotifyContext; establish errgroup and use it to supervise background tasks; convert ticker to context-aware periodicBandwidthCheck; run HTTP server under errgroup and add graceful shutdown; treat context.Canceled as normal exit
- relay: thread parent context through UDPProxyServer; add cancel func; make packet reader, workers, and cleanup tickers exit on ctx.Done; Stop cancels, closes listener and downstream UDP connections, and closes packet channel to drain workers
- proxy: drop earlier parent context hook for SNI proxy per review; rely on existing Stop() for graceful shutdown
Benefits:
- unified lifecycle and deterministic shutdown across components
- prevents leaked goroutines/tickers and closes sockets cleanly
- consolidated error handling via g.Wait(), with context cancellation treated as non-error
- sets foundation for child errgroups and future structured concurrency
