Include Aurora nav section in the sidebar's single-open accordion (v2.3.1)

Aurora's branded nav section had its own independent expand/collapse
state, so it stayed open regardless of which native menu section was
expanded — the one exception to the single-open accordion. Unified
under one openId ref (a sentinel value for Aurora alongside real
native-menu item ids) so expanding either collapses the other.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

aurora-admin.php

@@ -3,7 +3,7 @@
  * Plugin Name: Aurora Admin
  * Plugin URI: https://aurora.co
  * Description: A modern, fast WordPress admin interface.
- * Version: 2.3.0
+ * Version: 2.3.1
  * Author: Aurora
  * Text Domain: aurora-admin
  * Domain Path: /languages/
@@ -14,7 +14,7 @@
 
 defined("ABSPATH") || exit();
 
-define("AURORA_ADMIN_VERSION", "2.3.0");
+define("AURORA_ADMIN_VERSION", "2.3.1");
 define("AURORA_ADMIN_PATH", plugin_dir_path(__FILE__));
 define("AURORA_ADMIN_URL", plugins_url("aurora-admin/"));