Frontmatter: images in meta tags aren't resolved/bundled

[hybridherbst]

Describe the bug

I'm trying to piece together how to properly create

<meta property="og:image" content="https://my.page/images/example.png">

and similar.

I found

• Feature: social images (twitter/og) #504 which just points out links need to be absolute
• API to change head content #551 where a bunch of questions are asked and then just the transformHead API is linked
• the docs for https://vitepress.dev/reference/site-config#transformhead.

I tried to reference the image from frontmatter;
but while the direct markdown image reference is resolved and copied out, the frontmatter URL stays the same.

---
title: "Title"
description: "Desc"
head:
  - - meta
    - name: property="og:image"
      content: ./../src/relative/image.jpg
---

![An image](./../src/relative/image.jpg)

The above should in my opinion result in the image being copied over and the path resolved, and then the path could be further transformed in transformHead given some known absolute target URL where the website will end up at.

I also tried
content: url(./../src/relative/image.jpg)
in the hopes that this will trigger vite/vitepress understanding that's a file/url and should be treated as such, but that didn't work either.

Reproduction

It seems I can't upload images at vitepress.new, so can't add a repro there. I hope above explanation is sufficient.

Expected behavior

1. Ability to reference relative images from frontmatter so they're bundled properly
2. Docs for how to transform them to absolute URLs for use as meta tags

System Info

System:
    OS: Windows 10 10.0.22621
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 32.63 GB / 63.85 GB
  Binaries:
    Node: 18.13.0 - D:\Program Files\nodejs\node.EXE
    Yarn: 1.22.19 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 8.13.2 - D:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 113.0.5672.127
    Edge: Spartan (44.22621.1702.0), Chromium (113.0.1774.35)
    Internet Explorer: 11.0.22621.1
  npmPackages:
    vitepress: ^1.0.0-beta.1 => 1.0.0-beta.1

Additional context

There could also be additional processing steps involved on images (e.g. vite imagetools), so I think images referenced from frontmatter should be bundled/processed too.

Validations

• Check if you're on the latest VitePress version.
• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.