fix(frontend): scroll

frontend/src/routes/[mnemonic]/+page.svelte

@@ -39,8 +39,15 @@
 			: []
 	);
 
+	let prevMessageCount = 0;
+	let prevLastMessageId: string | undefined;
+
 	$effect(() => {
-		if (messages.length) {
+		const count = messages.length;
+		const lastId = lastMessage?._id;
+		if (count > prevMessageCount || (lastId && lastId !== prevLastMessageId)) {
+			prevMessageCount = count;
+			prevLastMessageId = lastId;
 			window.scrollTo(0, document.body.scrollHeight);
 		}
 	});