A host logs in to the new bus as node.<name>

The mesh names a machine's bus user node.<name>; the host dialled with the bare
name and every machine was refused the first time it reached the server:
"authentication error - User". Same string as the composed user list, or nothing
connects.

internal/link/hearing_nats.go

@@ -70,7 +70,10 @@ func dialNats(ctx context.Context, m Membership, timeout time.Duration) (Link, e
 	}
 	opts := []nats.Option{
 		nats.Secure(config),
-		nats.UserInfo(m.Node, m.Password),
+		// The mesh names a machine's bus user "node.<name>" (the controller's principal scheme), and
+		// the server refused the bare name the first time a machine dialled it: "authentication
+		// error - User". The same string the mesh composed into the user list, or nothing connects.
+		nats.UserInfo("node."+m.Node, m.Password),
 		nats.Name("mesh-host/" + m.Node),
 		nats.Timeout(timeout),
 		// A node that has silently lost its route notices, rather than holding a connection the