Add publisher line to HTML title page

The PDF shows "Contextual Dynamics Lab, Dartmouth College" below the
title but the HTML version was missing this line. Added the \@publisher
macro output to the maketitle configuration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: jeremymanning

tufte.cfg

@@ -35,6 +35,7 @@
 \renewcommand{\maketitle}{%
   \begingroup%
     \endparagraph\HCode{<h1>}\@title\HCode{</h1>}%
+    \HCode{<p class="subtitle publisher">}\@publisher\HCode{</p>}%
     \HCode{<p class="subtitle">}\@author\HCode{</p>}%
     \HCode{<p class="subtitle">}\@date\HCode{</p>}%
   \endgroup