Add settings_errors rendering in Settings API plugin_settings method

Ensures add_settings_error messages from change_settings_on_save are displayed on the settings page for consistent admin notice visibility.

Author: ajaydsouza

includes/admin/settings/class-settings-api.php

@@ -945,6 +945,7 @@ public function plugin_settings() {
 				<?php do_action( $this->prefix . '_settings_page_header_before' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.DynamicHooknameFound ?>
 				<h1><?php echo esc_html( $this->translation_strings['page_header'] ); ?></h1>
 				<?php do_action( $this->prefix . '_settings_page_header' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.DynamicHooknameFound ?>
+				<?php settings_errors( $this->prefix . '-notices' ); ?>
 
 				<div id="poststuff">
 				<div id="post-body" class="metabox-holder columns-2">