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/profile-header.php

@@ -61,7 +61,7 @@ extract($context, EXTR_SKIP); // phpcs:ignore WordPress.PHP.DontExtract.extract_
 			</div>
 		</div>
 		<div class="uc-header__actions">
-				<?php if (class_exists('AKSRT_User_Badges') && AKSRT_User_Badges::enabled()) : ?>
+				<?php if (class_exists('\AKSRT\User\Badges') && \AKSRT\User\Badges::enabled()) : ?>
 				<button type="button" class="btn-ghost btn-sm" data-aksrt-badges-open>
 					<i class="fas fa-award" aria-hidden="true"></i> <?php esc_html_e('我的徽章', 'aksrt'); ?>
 				</button>
@@ -85,7 +85,7 @@ extract($context, EXTR_SKIP); // phpcs:ignore WordPress.PHP.DontExtract.extract_
 	</div>
 </div>
 
-<?php if (class_exists('AKSRT_User_Badges') && AKSRT_User_Badges::enabled()) : ?>
+<?php if (class_exists('\AKSRT\User\Badges') && \AKSRT\User\Badges::enabled()) : ?>
 <div class="uc-modal" id="aksrt-badges-modal" hidden data-aksrt-badges-modal data-user-id="<?php echo (int) $user_id; ?>" data-can-wear="1">
 	<div class="uc-modal__overlay" data-aksrt-badges-close></div>
 	<div class="uc-modal__dialog" role="dialog" aria-modal="true" aria-label="<?php esc_attr_e('我的徽章', 'aksrt'); ?>">