machine: make each machine the source of truth for its configuration, sync it to cluster store

internal/machine/state.go

@@ -3,6 +3,7 @@ package machine
 import (
 	"encoding/json"
 	"fmt"
+	"net/netip"
 	"os"
 	"path/filepath"
 	"sync"
@@ -25,6 +26,8 @@ type State struct {
 	Name string
 	// Network specifies the network configuration for this machine.
 	Network *network.Config
+	// PublicIP is this machine's advertised public IP for ingress. Zero value if unset.
+	PublicIP netip.Addr `json:",omitempty"`
 	// MinStoreVersion is the cluster store version this machine must reach before participating.
 	// Per-actor vector (Corrosion actor UUID → max applied db_version) captured from an existing
 	// member at join time. Cleared once reached.