用户中心减层：收敛本人入口与 panel 契约

templates/parts/user-center/header.php

@@ -0,0 +1,5 @@
+<?php
+/** User center header. @package AKSRT */
+defined('ABSPATH') || exit;
+$context = is_array($args['context'] ?? null) ? $args['context'] : [];
+echo $context['header_html'] ?? ''; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped