Integrate light-mode.js into script.js, unify .panel/.side-panel classes
into .side-panel, scope theme variables to @media screen for proper
print light mode, and add page-break after chapo.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Rename nav.php to side-panel.php to host both navigation and table of contents
views. The panel uses data-view attributes to switch between nav and toc content.
Footer buttons updated to target the unified panel. TOC button now visible on desktop.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
