refactor(autoload): migrate theme classes to Composer PSR-4

Move 288 types from global AKSRT_* + inc/classes manual requires into
namespace AKSRT\{Domain} under src/AKSRT/, wire composer.json psr-4,
and slim bootstrap to helpers/modules/hooks only. Split multi-class
widget/gateway files, update admin contract audit paths, and document
the layout in ADR/README.

inc/helpers/user-center-renderers/sidebar-commerce.php

@@ -25,7 +25,7 @@ if ($show_wallet || $show_credits) :
 				<a class="uc-asset-mini__card flex1" href="<?php echo esc_url($assets_url); ?>">
 					<div class="uc-asset-mini__label muted-2-color em09"><?php esc_html_e('余额', 'aksrt'); ?><i class="ml6 fa fa-angle-right em12" aria-hidden="true"></i></div>
 					<div class="flex jsb ac">
-						<span class="font-bold c-blue-2"><?php echo esc_html(class_exists('AKSRT_Balance') ? AKSRT_Balance::format($wallet) : number_format_i18n($wallet, 2)); ?></span>
+						<span class="font-bold c-blue-2"><?php echo esc_html(class_exists('\AKSRT\Credits\Balance') ? \AKSRT\Credits\Balance::format($wallet) : number_format_i18n($wallet, 2)); ?></span>
 						<i class="fas fa-wallet em14 c-blue-2" aria-hidden="true"></i>
 					</div>
 				</a>