improve: center queue preview on its line

Add justifyContent: center to queue preview box to center it
horizontally on its own line for better visual balance.

Author: brandonkachen

cli/src/chat.tsx

@@ -717,6 +717,7 @@ export const Chat = ({
                 style={{
                   flexDirection: 'row',
                   width: '100%',
+                  justifyContent: 'center',
                 }}
               >
                 <text style={{ wrapMode: 'none' }}>