Show online in CLI & API when isOnline() reports so

cmd/headscale/cli/nodes.go

@@ -513,9 +513,7 @@ func nodesToPtables(
 		}
 
 		var online string
-		if lastSeen.After(
-			time.Now().Add(-5 * time.Minute),
-		) { // TODO: Find a better way to reliably show if online
+		if machine.Online {
 			online = pterm.LightGreen("online")
 		} else {
 			online = pterm.LightRed("offline")

machine.go

@@ -767,6 +767,7 @@ func (machine *Machine) toProto() *v1.Machine {
 		GivenName:   machine.GivenName,
 		Namespace:   machine.Namespace.toProto(),
 		ForcedTags:  machine.ForcedTags,
+		Online:      machine.isOnline(),
 
 		// TODO(kradalby): Implement register method enum converter
 		// RegisterMethod: ,