`fig-alt` does not populate the `alt` attribute on images for `format: hugo-md`

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

When the fig-alt attribute is set on an image, it propogates to data-fig-alt, not alt.

An additional case to check is when a caption is also set. Currently, the caption populates alt, but if fig-alt is set, it should override this.

Might be related to: https://github.com/quarto-dev/quarto-cli/issues/11478

Steps to reproduce

---
format: hugo-md
---

![](https://placehold.co/200x100.png){fig-alt="Alt text"}

Actual behavior

<img src="https://placehold.co/200x100.png" data-fig-alt="Alt text" />

Expected behavior

<img src="https://placehold.co/200x100.png" alt="Alt text" />

Your environment

No response

Quarto check output

Quarto 1.9.36
[✓] Checking environment information...
      Quarto cache location: /Users/charlottewickham/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.8.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.4.5: OK
      Typst version 0.14.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.9.36
      Path: /Applications/quarto/bin

[✓] Checking tools....................OK
      TinyTeX: v2026.04
      VeraPDF: 1.28.2
      Chromium: (not installed)
      Chrome Headless Shell: (not installed)

[✓] Checking LaTeX....................OK
      Using: TinyTex
      Path: /Users/charlottewickham/Library/TinyTeX/bin/universal-darwin
      Version: 2026

[✓] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
      Source: MacOS known location

[✓] Checking basic markdown render....OK

[✓] Checking R installation...........OK
      Version: 4.4.3
      Path: /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources
      LibPaths:
        - /Users/charlottewickham/Library/R/arm64/4.4/library
        - /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/library
      knitr: 1.45
      rmarkdown: 2.26

[✓] Checking Knitr engine render......OK

[✓] Checking Python 3 installation....OK
      Version: 3.11.11
      Path: /Users/charlottewickham/.local/share/uv/python/cpython-3.11.11-macos-aarch64-none/bin/python
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking Julia installation...