ax(node): replace prose comment on DefaultTransportConfig with usage example

AX Principle 2: comments must show HOW with real values, not restate what
the type signature already says. "returns sensible defaults" adds zero
information — the concrete call pattern teaches agents exactly how to use it.

Co-Authored-By: Charon <charon@lethean.io>

pkg/node/transport.go

@@ -38,7 +38,9 @@ type TransportConfig struct {
 	PongTimeout    time.Duration // Timeout waiting for pong
 }
 
-// DefaultTransportConfig returns sensible defaults.
+// cfg := node.DefaultTransportConfig()
+// cfg.ListenAddr = ":9095"
+// cfg.TLSCertPath = "/etc/lethean/tls.crt"
 func DefaultTransportConfig() TransportConfig {
 	return TransportConfig{
 		ListenAddr:     ":9091",