Fix: disable org-babel evaluation during export

org-publish was trying to resolve babel :var references (e.g.
data=previous-block) in the chapter code examples, causing export
to crash. Since this is a documentation book, code blocks should be
displayed verbatim, not executed. Setting org-export-use-babel nil
prevents any babel processing during HTML export.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: DavidLiedle

publish.el

@@ -16,7 +16,10 @@
       org-html-validation-link nil
       org-html-use-infojs nil
       org-export-with-smart-quotes t
-      org-export-with-sub-superscripts nil)
+      org-export-with-sub-superscripts nil
+      ;; Never evaluate code blocks during export — this is a book,
+      ;; not a notebook. Blocks are displayed verbatim.
+      org-export-use-babel nil)
 
 ;; Use htmlize for syntax highlighting when available
 (when (require 'htmlize nil t)