inline <code> tags get turned into block-level elements

Not sure if CKEditor 5 handles pre tags differently, but I'm not able to make the pre tags appear inline. I edited the source in my content so the pre tags would be inside a paragraph, but as soon as I take it out of source code view, the WYSIWYG has put paragraph tags around the pre tags again.

I found a pretty simple way to make this work the way I would have expected: change the XPath query within highlight_php_highlight() to only select code tags that are directly within pre tags. Since this aligns with how Drupal core marks up "code blocks", this makes sense as a solution.