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/credits-transactions.php

@@ -18,8 +18,8 @@ defined('ABSPATH') || exit;
 	</div>
 	<?php
 	$credits_page = max(1, isset($_GET['credits_page']) ? (int) $_GET['credits_page'] : 1);
-	if (class_exists('AKSRT_Credits')) {
-		$log = AKSRT_Credits::get_log(['user_id' => $user_id, 'page' => $credits_page, 'per_page' => 10]);
+	if (class_exists('\AKSRT\Credits\Credits')) {
+		$log = \AKSRT\Credits\Credits::get_log(['user_id' => $user_id, 'page' => $credits_page, 'per_page' => 10]);
 	} else {
 		$log = ['items' => [], 'total' => 0];
 	}