feat: put Template Library behind WU_TEMPLATE_LIBRARY_ENABLED feature flag (#599)

* Revert "feat: rename Primary Domain to Main WP Multisite WaaS Domain with red toggle and confirmation (#438)"

This reverts commit a205ea8.

* feat: put Template Library behind WU_TEMPLATE_LIBRARY_ENABLED feature flag

The Template Library admin page is now hidden by default since server-side
functionality is not complete. Developers can enable it by defining:

    define('WU_TEMPLATE_LIBRARY_ENABLED', true);

in wp-config.php before the plugin loads.

- Add WU_TEMPLATE_LIBRARY_ENABLED constant to constants.php (defaults to false)
- Wrap Template_Library_Admin_Page instantiation with feature flag check
- Include inline documentation explaining the feature flag purpose

Author: superdav42

constants.php

@@ -23,3 +23,17 @@
 if ( ! defined('WP_ULTIMO_PLUGIN_BASENAME')) {
 	define('WP_ULTIMO_PLUGIN_BASENAME', plugin_basename(WP_ULTIMO_PLUGIN_FILE));
 }
+
+/**
+ * Feature flag: Enable Template Library.
+ *
+ * When set to true, enables the Template Library admin page.
+ * Server-side functionality is not complete, so this defaults to false.
+ * Developers can enable this by defining WU_TEMPLATE_LIBRARY_ENABLED as true
+ * in wp-config.php before the plugin loads.
+ *
+ * @since 2.5.0
+ */
+if ( ! defined('WU_TEMPLATE_LIBRARY_ENABLED')) {
+	define('WU_TEMPLATE_LIBRARY_ENABLED', false);
+}

inc/class-wp-ultimo.php

@@ -855,7 +855,18 @@ protected function load_admin_only_pages(): void {
 
 		new WP_Ultimo\Admin_Pages\Setup_Wizard_Admin_Page();
 
-		new WP_Ultimo\Admin_Pages\Template_Library_Admin_Page();
+		/**
+		 * Template Library Admin Page.
+		 *
+		 * This is behind a feature flag as server-side functionality
+		 * is not yet complete. Define WU_TEMPLATE_LIBRARY_ENABLED as true
+		 * in wp-config.php to enable for development/testing.
+		 *
+		 * @since 2.5.0
+		 */
+		if (defined('WU_TEMPLATE_LIBRARY_ENABLED') && WU_TEMPLATE_LIBRARY_ENABLED) {
+			new WP_Ultimo\Admin_Pages\Template_Library_Admin_Page();
+		}
 
 		do_action('wp_ultimo_admin_pages');
 	}