fix: drop contentsRAF null reset to prevent reactive loop

Author: Algorithm5838

src/lib/components/chat/Chat.svelte

@@ -938,7 +938,6 @@
 		cancelAnimationFrame(contentsRAF);
 		contentsRAF = requestAnimationFrame(() => {
 			getContents();
-			contentsRAF = null;
 		});
 	} else {
 		artifactContents.set([]);