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.

templates/pages/page-verify-email.php

@@ -14,14 +14,14 @@ $redirect_url   = '';
 
 if ($_SERVER['REQUEST_METHOD'] === 'POST') {
 	if (isset($_POST['verify_email_resend'])) {
-		$result = AKSRT_Auth_Service::resend_email_verification($_POST);
+		$result = \AKSRT\Auth\Service::resend_email_verification($_POST);
 		if (!empty($result['success'])) {
 			$verify_success = $result['message'] ?? __('验证邮件已重新发送，请注意查收。', 'aksrt');
 		} else {
 			$verify_error = $result['error'] ?? __('验证邮件发送失败，请稍后重试。', 'aksrt');
 		}
 	} elseif (isset($_POST['verify_email_submit'])) {
-		$result = AKSRT_Auth_Service::verify_email_code_submission($_POST);
+		$result = \AKSRT\Auth\Service::verify_email_code_submission($_POST);
 		if (!empty($result['success'])) {
 			$verify_success = $result['message'] ?? __('邮箱验证成功，即将进入你的账号。', 'aksrt');
 			$redirect_url   = $result['redirect'] ?? '';
@@ -31,7 +31,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
 	}
 }
 
-$verify_context = AKSRT_Auth_Service::get_email_verification_context($_GET);
+$verify_context = \AKSRT\Auth\Service::get_email_verification_context($_GET);
 if ($verify_error === '' && !empty($verify_context['error'])) {
 	$verify_error = $verify_context['error'];
 }
@@ -128,7 +128,7 @@ get_header();
 				// method 缺失（历史账号 / meta 被外部清理）→ 回退到设置默认值
 				$resend_method = in_array($verify_method, ['link', 'code'], true)
 					? $verify_method
-					: (class_exists('AKSRT_Settings') ? AKSRT_Settings::registration_verification_method() : 'link');
+					: (class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::registration_verification_method() : 'link');
 			?>
 			<?php if ($verify_email !== '') : ?>
 			<p class="auth-card__subtitle"><?php echo esc_html(sprintf(__('当前待验证邮箱：%s', 'aksrt'), $verify_email)); ?></p>