Admit a port from the machine's own local network, and never a public subnet (issue 154, ADR 0340)

A local service could only be declared public, which says the internet. local-network is a source and a reach: the private network and the private networks the machine reported on a link facing outside, judged here, shown by plan and node, and said in the rule set when there are none.

internal/inventory/machine.go

@@ -36,7 +36,16 @@ type MadeOf struct {
 	BootedAt      *time.Time          `json:"booted_at"`
 	Timezone      string              `json:"timezone"`
 	Filesystems   []MountedFilesystem `json:"filesystems"`
-	Unknown       map[string]string   `json:"unknown"`
+	// Networks is every network the machine is directly attached to on a link facing outside it, as
+	// link and network (novox/hq ADR 0340 §7): what a port reached from `local-network` resolves from.
+	Networks []AttachedNetwork `json:"networks"`
+	Unknown  map[string]string `json:"unknown"`
+}
+
+// AttachedNetwork is one network a machine said it is attached to, and the link it is on.
+type AttachedNetwork struct {
+	Link    string `json:"link"`
+	Network string `json:"network"`
 }
 
 // MountedFilesystem is one local filesystem a machine has mounted.