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.

src/AKSRT/Admin/Schema/SchemaShopContact.php

@@ -0,0 +1,30 @@
+<?php
+/**
+ * @package AKSRT
+ */
+
+namespace AKSRT\Admin\Schema;
+
+defined('ABSPATH') || exit;
+
+class SchemaShopContact {
+
+    public static function build(): array {
+        return [
+            'key'        => 'contact',
+            'title'      => '客服配置',
+            'version'    => '1.0.0',
+            'option_key' => 'aksrt_settings',
+            'groups'     => [
+                ['key' => 'button', 'title' => '客服按钮', 'fields' => [
+                    ['key' => 'shop_contact_msg_s', 'label' => '显示客服按钮', 'type' => 'switch', 'default' => true],
+                    ['key' => 'shop_contact_name', 'label' => '按钮文案', 'type' => 'input', 'default' => '联系客服'],
+                    ['key' => 'shop_contact_note', 'label' => '客服备注', 'type' => 'textarea', 'default' => ''],
+                ]],
+                ['key' => 'channels', 'title' => '联系方式', 'fields' => [
+                    ['key' => 'shop_contact_more', 'label' => '多客服联系方式', 'type' => 'textarea', 'default' => '', 'help' => '每行一个：名称|图标|链接|二维码图片 URL'],
+                ]],
+            ],
+        ];
+    }
+}