Add `ng add` for mcp

### Which @angular/* package(s) are relevant/related to the feature request?

_No response_

### Description

Having https://angular.dev/ai/mcp showcasing what to do is great. Having to configure things manually is not that great. What about having an ng add command which creates those files?

### Proposed solution

`ng add mcp` -> it should ask the user which files it should create

### Alternatives considered

Configure it manually!

从 https://angular.dev/ai/mcp 上的 MCP 指南和提议的 `ng add mcp` 命令开始。确定该命令应提供创建哪些配置文件，以及提示应如何选择这些文件；完成标准是该命令创建所选文件并支持文档中说明的 MCP 设置。

由索引模型根据 Issue 内容生成。