fix: remove 500-message limit to prevent scrollbar jumping in long conversations

Fixes #7052

The issue was caused by array index shifting when conversations exceeded 500 messages.
Each new message would cause the oldest message to be dropped and all indices to shift,
making Virtuoso lose track of the current scroll position.

This fix removes the message limit entirely and lets Virtuoso handle virtualization
of all messages efficiently, completely eliminating the index shifting problem.

Author: roomote

webview-ui/src/components/chat/ChatView.tsx

@@ -897,11 +897,9 @@ const ChatViewComponent: React.ForwardRefRenderFunction<ChatViewRef, ChatViewPro
 	useMount(() => textAreaRef.current?.focus())
 
 	const visibleMessages = useMemo(() => {
-		const currentMessageCount = modifiedMessages.length
-		const startIndex = Math.max(0, currentMessageCount - 500)
-		const recentMessages = modifiedMessages.slice(startIndex)
-
-		const newVisibleMessages = recentMessages.filter((message: ClineMessage) => {
+		// Remove the 500-message limit to prevent array index shifting
+		// Virtuoso handles virtualization efficiently for large lists
+		const newVisibleMessages = modifiedMessages.filter((message: ClineMessage) => {
 			if (everVisibleMessagesTsRef.current.has(message.ts)) {
 				const alwaysHiddenOnceProcessedAsk: ClineAsk[] = [
 					"api_req_failed",