cluster: introduce NodeID and ZoneID types

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/machine.go

@@ -12,7 +12,7 @@ type Machine struct {
 	zone   *Zone
 	logger `json:"-" yaml:"-"`
 
-	ID   int
+	ID   NodeID
 	Name string `json:"-" yaml:"-"`
 
 	Inactive        bool         `json:"inactive,omitempty"     yaml:"inactive,omitempty"`
@@ -74,7 +74,7 @@ func (m *Machine) SetGateway(enabled bool) error {
 }
 
 // Zone indicates the [Zone] this machine belongs to
-func (m *Machine) Zone() int {
+func (m *Machine) Zone() ZoneID {
 	return m.zone.ID
 }