Every serving principal may answer the services discovery for what it serves; the controller announces its seat (hq ADR 0197)

Grants: a principal that serves tools subscribes $SRV.PING/$SRV.INFO and those questions under
each name it serves — its own and no other's; the tool runtime and people may ask. The controller
answers discovery for the mesh-controller seat in NATS's services format, one endpoint per verb it
serves, with the seat's description and schema. module list --json says which modules declare tools,
so the console expects an announcement only from those.

cmd/mesh-controller/push.go

@@ -151,6 +151,12 @@ func serve(ctx context.Context) error {
 		return err
 	}
 	defer stopServing()
+	// And says so on the bus (novox/hq ADR 0197): what it serves, as the NATS services protocol asks.
+	stopAnnouncing, err := bus.Announce(seatAnnouncement(handlers), log.New(os.Stdout, "", log.LstdFlags))
+	if err != nil {
+		return err
+	}
+	defer stopAnnouncing()
 
 	return server.Serve(ctx)
 }