feat(chat): add conversation selection and enhance message rendering

- Add currentConversationId prop to ChatContainer for loading selected conversations
- Implement logic to load messages when conversation is selected and clear when deselected
- Improve user message rendering with proper whitespace handling
- Enhance MarkdownRenderer with content normalization and adjusted spacing for better readability
- Add paragraph styling to markdown output for improved layout

This enables users to switch between conversations seamlessly and provides cleaner message display.

components/chat/ChatMessage.tsx

@@ -34,9 +34,9 @@ export function ChatMessage({
             : "bg-[var(--surface)] text-[var(--foreground)]"
         }`}
       >
-        <div className="whitespace-pre-wrap break-words">
+        <div className="break-words">
           {isUser ? (
-            message.content
+            <div className="whitespace-pre-wrap">{message.content}</div>
           ) : (
             <MarkdownRenderer content={message.content} />
           )}