feat(auth): WeixinGzh QR/code login REST + server push endpoint

Add subscribe-mode static QR + keyword code login, service-mode scene QR
polling, server URL verification, and modal-auth form/poll wiring.

functions.php

@@ -137,6 +137,9 @@ if (get_option('aksrt_flushed_version') !== AKSRT_VERSION) {
 \AKSRT\Core\Scripts::get_instance()->init();
 \AKSRT\Admin\Admin::get_instance()->init();
 \AKSRT\Auth\OAuth::get_instance()->init();
+if (class_exists('\AKSRT\Auth\WeixinGzh')) {
+    \AKSRT\Auth\WeixinGzh::get_instance()->init();
+}
 
 // 初始化代理登录（根据配置模式选择性加载）
 $aksrt_proxy_mode = \AKSRT\Settings\Settings::oauth_proxy_mode();