Remove unnecessary placeholder directories

The CI publish script creates directories as needed via cp -a, and
pages.jl dynamically discovers folders. No pre-existing dirs required.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas