node-tools: start no bundle again once the runtime itself is stopping (issue 1126)

The service manager stops node-tools by signalling its whole group, so every
bundle gets SIGTERM with it; the launcher took each exit for a fault and started
the bundle again, for the 15 s the runtime took to stop. On ace's reboot of
2026-10-28 those restarted bundles dialled the system bus once polkit and the bus
had stopped, the bus and polkit came back during the shutdown, nothing stopped
them a second time, and the reboot waited 29 minutes on its job timeout.

ShutDown, called first on SIGTERM, keeps any bundle from starting again, by a
restart or by a call; a running one still answers.

node-tools/cmd/node-tools/main.go

@@ -26,6 +26,7 @@ import (
 	"github.com/novox/mesh-tools/node-tools/internal/alive"
 	"github.com/novox/mesh-tools/node-tools/internal/bus"
 	"github.com/novox/mesh-tools/node-tools/internal/console"
+	"github.com/novox/mesh-tools/node-tools/internal/launch"
 	"github.com/novox/mesh-tools/node-tools/internal/provide"
 	"github.com/novox/mesh-tools/node-tools/internal/runtime"
 )
@@ -91,6 +92,9 @@ func main() {
 	signals := make(chan os.Signal, 1)
 	signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)
 	<-signals
+	// First of all: the service manager signalled every bundle with this process, and none is started again
+	// (issue 1126).
+	launch.ShutDown()
 	stopSaying()
 	stopProviding()
 	stop()