HarmonyOS Application Development - Imitating WeChat Chat Message List

This example demonstrates how to create a chat application interface similar to WeChat using ArkTS. The page structure includes a scrollable message list and a button to dynamically add new messages. The core code is as follows: 1. The `Msg` class defines the message type (sent or received). 2. The `MsgDataSource` class implements the data source interface, manages the message list, and provides add/delete operations. 3. The page uses the `List` component to display the message list, with `LazyForEach` to dynamically load new messages as the user scrolls.