feat: serve Monaco editor from local bundle instead of CDN

[Copilot]

Monaco editor was loaded via jsdelivr.net CDN, causing "load failed" on air-gapped or CDN-blocked servers.

Changes

• vite.config.ts — add vite-plugin-monaco-editor plugin; builds Monaco workers into dist/monacoeditorwork/ and wires up MonacoEnvironment.getWorkerUrl automatically
• main.ts — replace CDN loader.config({ paths: { vs: '...' } }) with direct local import:

  import * as monaco from 'monaco-editor';
  loader.config({ monaco });

  This bypasses @monaco-editor/loader's AMD/CDN path entirely in favour of the already-bundled monaco-editor npm package
• package.json — add vite-plugin-monaco-editor@1.1.0 as devDependency

Original prompt

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This section details on the original issue you should resolve

<issue_title>希望Monaco编辑器从cdn部署改为本地部署</issue_title>
<issue_description>### Description / 描述

我在服务器上编辑mcp服务器时遇到webui加载失败错误，看了一下网页源码发现cdn部署的monaco无法使用，我的服务器ping不通，所以希望改成本地部署的编辑器

Use Case / 使用场景

Willing to Submit PR? / 是否愿意提交PR？

• Yes, I am willing to submit a PR. / 是的，我愿意提交 PR。

Code of Conduct

• I have read and agree to abide by the project's Code of Conduct. /
  </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes 希望Monaco编辑器从cdn部署改为本地部署 #5587

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