Add Site Metadata Endpoint and API Key Management

- Introduced a new Site Metadata endpoint (`GET /wp-json/igny8/v1/site-metadata/`) for retrieving available post types and taxonomies, including counts.
- Added API key input in the admin settings for authentication, with secure storage and revocation functionality.
- Implemented a toggle for enabling/disabling two-way sync operations.
- Updated documentation to reflect new features and usage examples.
- Enhanced permission checks for REST API calls to ensure secure access.

igny8-wp-integration-plugin/includes/class-igny8-api.php

@@ -32,6 +32,13 @@ class Igny8API {
      */
     private $access_token = null;
     
+    /**
+     * Whether authentication is via API key (true) or tokens (false)
+     *
+     * @var bool
+     */
+    private $api_key_auth = false;
+    
     /**
      * Refresh token
      *
@@ -46,9 +53,17 @@ class Igny8API {
         if (function_exists('igny8_get_secure_option')) {
             $this->access_token = igny8_get_secure_option('igny8_access_token');
             $this->refresh_token = igny8_get_secure_option('igny8_refresh_token');
+            $api_key = igny8_get_secure_option('igny8_api_key');
         } else {
             $this->access_token = get_option('igny8_access_token');
             $this->refresh_token = get_option('igny8_refresh_token');
+            $api_key = get_option('igny8_api_key');
+        }
+
+        // If an API key is provided, prefer it as the access token
+        if (!empty($api_key)) {
+            $this->access_token = $api_key;
+            $this->api_key_auth = true;
         }
     }