refactor(classes): organize inc/classes into domain folders

Move ~94 root class shells and root *-traits into domain directories
(core, auth, user, credits, content, payment/gateways, forum, shop,
sms, ai, messages, extensions, widgets, settings, admin). Update
bootstrap require paths, co-locate traits with owners, fix forum/user
relative requires, drop duplicate shop controller requires, and wire
home-modules load. Path-only; class names and init order unchanged.

inc/classes/sms/class-aksrt-sms-provider.php

@@ -0,0 +1,49 @@
+<?php
+/**
+ * AKSRT SMS Provider Interface
+ *
+ * 统一短信供应商接口。所有 SMS adapter 必须实现此接口。
+ *
+ * @package AKSRT
+ */
+
+defined('ABSPATH') || exit;
+
+interface AKSRT_SMS_Provider {
+
+    /**
+     * 供应商唯一标识
+     */
+    public function get_key(): string;
+
+    /**
+     * 供应商显示名称
+     */
+    public function get_label(): string;
+
+    /**
+     * 校验配置完整性，返回缺失字段列表
+     *
+     * @param array $config SMS 配置
+     * @return array 缺失的字段名列表，空数组表示配置完整
+     */
+    public function validate_config(array $config): array;
+
+    /**
+     * 发送短信验证码
+     *
+     * @param string $phone  手机号
+     * @param string $code   验证码
+     * @param array  $config SMS 配置
+     * @return array{success: bool, message: string, transport?: string}
+     */
+    public function send_code(string $phone, string $code, array $config): array;
+
+    /**
+     * 获取供应商运行时状态
+     *
+     * @param array $config SMS 配置
+     * @return array{configured: bool, available: bool, verified: bool, transport: string, missing_fields: array}
+     */
+    public function get_status(array $config): array;
+}