Add artmap polling to discover sACN unicast receivers

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tendrils.go

@@ -69,6 +69,7 @@ type Tendrils struct {
 	DebugShure     bool
 	DebugYamaha    bool
 	DebugBroadcast bool
+	DebugArtmap    bool
 }
 
 func New() *Tendrils {
@@ -346,4 +347,8 @@ func (t *Tendrils) pollNode(node *Node) {
 			t.probeDanteDevice(ip)
 		}
 	}
+
+	for _, ip := range ips {
+		t.probeArtmap(ip)
+	}
 }