Improve formatting of lists

List layout adjustments in the SKS LaTeX path: list item spacing and the
surrounding document style tuned in list.py, latex_util.py,
document.sty, and block.k.

Assembled from dev commit f34e66a4dbfb.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

sks/block/block.k

@@ -135,3 +135,9 @@ only makes some vertical space. @@
 *s*
 \end{multicols}
 @@
+
+@@left_right.k left | right : Text left- and right- justified on one line @@
+
+@@left_right.tex ::
+  \makebox[\dimexpr\linewidth+\labelindent\relax]{*left*\hfill *right*}
+@@