fix(layout): restore Zibll float dual-column so content no longer overlaps sidebar

Align main shells to main.container > .content-wrap + .sidebar siblings, drop
content-shell padding on dual-column hosts, and remove route flex overrides that
disabled the negative-margin sidebar math.

templates/pages/page-categories.php

@@ -49,7 +49,7 @@ if ($page_title === '') {
 <?php
 if (function_exists('aksrt_archive_open_shell')) {
 	aksrt_archive_open_shell([
-		'main_class'  => 'site-main container content-shell content-shell--page',
+		'main_class'  => 'site-main container ',
 		'has_sidebar' => false,
 		'page_kind'   => 'categories',
 	]);