improve: missing env properties for Content Loader when render is specified

[nekomeowww]

Summary

For general VitePress page renders, properties of env are available for markdown-it plugins to peek file path related info:

vitepress/src/node/markdownToVue.ts

Lines 113 to 122 in 36e0c1a

	// reset env before render
	const env: MarkdownEnv = {
	path: file,
	relativePath,
	cleanUrls,
	includes,
	realPath: fileOrig,
	localeIndex
	}
	const html = md.render(src, env)

However, for content loader, if specified such

export default createContentLoader('/**/*.md', {
  render: true,
  transform() {
    return []
  },
})

content loader function, with our Lazy loading blurred thumbnails | Nólëbase Integrations markdown-it plugin where env.path and env.relativePath are required, since users are not allowed to toggle these unsupported markdown-it plugins for content loaders, they will not be able to use content loaders with markdown-it-unlazy-img together.

I found the code here, for content loaderss, within the render function, env properties are not injected as what VitePress's render would do:

vitepress/src/node/contentLoader.ts

Line 147 in 36e0c1a

const html = render ? md.render(src) : undefined

Proposal

• Add env properties
• Allow users to reconfigure md.use

[brc-dd]

Duplicate of #4331

Please track it instead. We actually need a bunch of refactoring for this to work correctly. I'll do it next when I get time.