watch for peer endpoint changes and preserve in machine state

internal/machine/network/wireguard.go

@@ -3,6 +3,7 @@ package network
 import (
 	"fmt"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+	"net/netip"
 	"time"
 	"uncloud/internal/secret"
 )
@@ -14,6 +15,12 @@ const (
 	WireGuardKeepaliveInterval = 25 * time.Second
 )
 
+type EndpointChangeEvent struct {
+	PublicKey secret.Secret
+	// Endpoint is the new endpoint of the peer.
+	Endpoint netip.AddrPort
+}
+
 // NewMachineKeys generates a new WireGuard private and public key pair.
 func NewMachineKeys() (privKey, pubKey secret.Secret, err error) {
 	wgPrivKey, err := wgtypes.GeneratePrivateKey()