feat: Add product images support with WP Media Library integration

- Add WP Media Library integration for product and variation images
- Support images array (URLs) conversion to attachment IDs
- Add images array to API responses (Admin & Customer SPA)
- Implement drag-and-drop sortable images in Admin product form
- Add image gallery thumbnails in Customer SPA product page
- Initialize WooCommerce session for guest cart operations
- Fix product variations and attributes display in Customer SPA
- Add variation image field in Admin SPA

Changes:
- includes/Api/ProductsController.php: Handle images array, add to responses
- includes/Frontend/ShopController.php: Add images array for customer SPA
- includes/Frontend/CartController.php: Initialize WC session for guests
- admin-spa/src/lib/wp-media.ts: Add openWPMediaGallery function
- admin-spa/src/routes/Products/partials/tabs/GeneralTab.tsx: WP Media + sortable images
- admin-spa/src/routes/Products/partials/tabs/VariationsTab.tsx: Add variation image field
- customer-spa/src/pages/Product/index.tsx: Add gallery thumbnails display

includes/Compat/NavigationRegistry.php

@@ -13,7 +13,7 @@ if ( ! defined('ABSPATH') ) exit;
  */
 class NavigationRegistry {
     const NAV_OPTION = 'wnw_nav_tree';
-    const NAV_VERSION = '1.0.0';
+    const NAV_VERSION = '1.0.1'; // Bumped to add Customer SPA settings
     
     /**
      * Initialize hooks
@@ -29,6 +29,15 @@ class NavigationRegistry {
      * Build the complete navigation tree
      */
     public static function build_nav_tree() {
+        // Check if we need to rebuild (version mismatch)
+        $cached = get_option(self::NAV_OPTION, []);
+        $cached_version = $cached['version'] ?? '';
+        
+        if ($cached_version === self::NAV_VERSION && !empty($cached['tree'])) {
+            // Cache is valid, no need to rebuild
+            return;
+        }
+        
         // Base navigation tree (core WooNooW sections)
         $tree = self::get_base_tree();
         
@@ -182,6 +191,7 @@ class NavigationRegistry {
             ['label' => __('Tax', 'woonoow'), 'mode' => 'spa', 'path' => '/settings/tax'],
             ['label' => __('Customers', 'woonoow'), 'mode' => 'spa', 'path' => '/settings/customers'],
             ['label' => __('Notifications', 'woonoow'), 'mode' => 'spa', 'path' => '/settings/notifications'],
+            ['label' => __('Customer SPA', 'woonoow'), 'mode' => 'spa', 'path' => '/settings/customer-spa'],
             ['label' => __('Developer', 'woonoow'), 'mode' => 'spa', 'path' => '/settings/developer'],
         ];