cluster: decouple RingID from WireguardInterfaceID

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

pkg/cluster/errors.go

@@ -1,6 +1,13 @@
 package cluster
 
-import "errors"
+import (
+	"errors"
+	"io/fs"
+
+	"darvaza.org/core"
+
+	"git.jpi.io/amery/jpictl/pkg/rings"
+)
 
 var (
 	// ErrInvalidName indicates the name isn't valid
@@ -14,3 +21,9 @@ var (
 	// the intended purpose
 	ErrInvalidNode = errors.New("invalid node")
 )
+
+// ErrInvalidRing returns an error indicating the [rings.RingID]
+// can't be used for the intended purpose
+func ErrInvalidRing(ringID rings.RingID) error {
+	return core.QuietWrap(fs.ErrInvalid, "invalid ring %v", ringID)
+}