link-citations: true incompletely implemented in ipynb

Bug description

Using link-citations: true makes citations hyperlink to the corresponding bibliography entries. This works fine for html and pdf outputs. However, in ipynb the citation is a link, but the target is not defined.

Minimal example:

test.qmd

---
bibliography: references.bib
link-citations: true
---

Citation: a book @Author2006 and a paper @Author2020.

::: {#refs}
:::

Command:

quarto render temp.qmd --to ipynb

This results in a in notebook with a single markdown cell:

# 

Citation: a book Author1 ([2006](#ref-author2006)) and
a paper Author3 ([2020](#ref-author2020)).

Author1, X., and Z. Author2. 2006. “Some title.” In *Some journal*, 1: 100-115

Author3, A. 2020. “Another title.” *Another journal.*  2: 304-315

Expected result (I think), markdown cell:

# 

Citation: a book Author1 ([2006](#ref-author2006)) and
a paper Author3 ([2020](#ref-author2020)).

<span id="ref-author2006"></span>Author1, X., and Z. Author2. 2006. “Some title.” *Some journal*, 1: 100-115

<span id="ref-author2020"></span>Author3, A. 2020. “Another title.” *Another journal.*  2: 304-315

I am using VSCode to write qmd files, but render them on the command line (Mac OS 11.7), using quarto installed directly from the GitHub repo, commit id #82eae91a0 (which is why quarto --version gives 99.9.9)

Checklist

• Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
• Please format your issue so it is easier for us to read the bug report.
• Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
• Please document the operating system you're running. If on Linux, please provide the specific distribution.

Start with the minimal test.qmd and references.bib example, then run quarto render temp.qmd --to ipynb and inspect the generated markdown cell. Compare the citation targets with the bibliography entries; done means each #ref-... citation target is defined in the notebook output.