Bump version to 2.1.0, add CHANGELOG.md

Covers this session's work: free/paid feature gating, real
auroraplugins.com license validation, and file-integrity tamper
protection for the license gate.

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: 2.0.0
+ * Version: 2.1.0
  * Author: Aurora
  * Text Domain: aurora-admin
  * Domain Path: /languages/
@@ -14,7 +14,7 @@
 
 defined("ABSPATH") || exit();
 
-define("AURORA_ADMIN_VERSION", "2.0.0");
+define("AURORA_ADMIN_VERSION", "2.1.0");
 define("AURORA_ADMIN_PATH", plugin_dir_path(__FILE__));
 define("AURORA_ADMIN_URL", plugins_url("aurora-admin/"));