refactor(core): add headless run and auto-restart

- Run without console by default
- Log to file once console hidden
- Recover panics in background goroutines
- Restart agent after unexpected errors
- Use shared instance launch helper

lib/agent/agent.go

@@ -100,16 +100,16 @@ func (a *Agent) Serve() error {
 		return fmt.Errorf("listen %s: %w", a.addr, err)
 	}
 
-	fmt.Printf("win64_mp %s\nListening on http://%s\nPress Ctrl+C to stop.\n", config.Version, a.addr)
+	helpers.Log.Printf("win64_mp %s listening on http://%s", config.Version, a.addr)
 
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer stop()
-	go func() {
+	helpers.Go("shutdown", func() {
 		<-ctx.Done()
 		shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 		defer cancel()
 		_ = a.server.Shutdown(shutdownCtx)
-	}()
+	})
 
 	if err := a.server.Serve(listener); err != nil && !errors.Is(err, http.ErrServerClosed) {
 		return fmt.Errorf("serve: %w", err)