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!

從 https://angular.dev/ai/mcp 上的 MCP 指南和提議的 `ng add mcp` 命令開始。確定該命令應提供建立哪些設定檔，以及提示應如何選取這些檔案；完成標準是該命令建立所選檔案並支援文件中說明的 MCP 設定。

由索引模型根據 Issue 內容生成。