Fix Typst definition list structure for PDF/UA-1

Preserve terms element structure in definition lists for PDF/UA-1
validation. Uses nested show rule instead of .map().join() which
destroyed the list structure.

Suggested by @mcanouil (PR #13249 discussion)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: gordonwoodhull

src/resources/formats/typst/pandoc/quarto/definitions.typ

@@ -17,13 +17,15 @@
   #stack(dir: ltr, spacing: 3pt, super[#num], contents)
 ]
 
+// Use nested show rule to preserve list structure for PDF/UA-1 accessibility
+// See: https://github.com/quarto-dev/quarto-cli/pull/13249#discussion_r2678934509
 #show terms: it => {
-  it.children
-    .map(child => [
-      #strong[#child.term]
-      #block(inset: (left: 1.5em, top: -0.4em))[#child.description]
-      ])
-    .join()
+  show terms.item: item => {
+    set text(weight: "bold")
+    item.term
+    block(inset: (left: 1.5em, top: -0.4em))[#item.description]
+  }
+  it
 }
 
 // Some quarto-specific definitions.

tests/docs/smoke-all/pdf-standard/ua1-definition-list.qmd

@@ -0,0 +1,26 @@
+---
+title: "UA-1 definition list accessibility"
+lang: en
+pdf-standard: ua-1
+keep-typ: true
+_quarto:
+  tests:
+    typst:
+      # Definition lists should pass PDF/UA-1 validation
+      # Fix: https://github.com/quarto-dev/quarto-cli/pull/13249#discussion_r2678934509
+      noErrors: default
+---
+
+# Definition List Test
+
+This tests that definition lists are accessible in PDF/UA-1.
+
+Term 1
+:   Definition for term 1
+
+Term 2
+:   Definition for term 2
+
+Term 3
+:   Definition for term 3 with more detailed explanation
+    that spans multiple lines.