Simple tables incorrectly rendered in markdown cell output

Bug description

Latest versions of the vscode extension cover some pandoc markdown special syntaxes in jupyter notebooks. One exception are simple markdown tables. Given that AFAICS they are not documented in https://quarto.org/docs/authoring/tables.html, perhaps they are not intended to be part of quarto markdown, but this example produces them and they are correctly rendered in the preview panel (not the cell output), so if that were the case the situation is a bit misleading.

Steps to reproduce

Create a notebook, add a markdown cell with:

  Right     Left     Center     Default
-------     ------ ----------   -------
     12     12        12            12
    123     123       123          123
      1     1          1             1

and execute it.

Actual behavior

Expected behavior

A correctly formed table, perhaps not a final rendering as:

Your environment

• IDE: VSCode 1.99.3 & Positron 2025.04.0
• macOS Sequoia 15.1
• Quarto Extension 1.121.0

Start by reproducing the issue in the Quarto VSCode extension with the simple-table markdown cell from the report, then compare its cell output with the preview panel. The issue provides no source files or tests; done means the simple table is correctly rendered in cell output, consistent with the expected behavior.