Fix license generation and checkout domain field bugs

- Add WooCommerce Checkout Blocks support for domain field
- Create CheckoutBlocksIntegration for block-based checkout
- Create StoreApiExtension for Store API domain handling
- Add checkout-blocks.js for frontend domain field in blocks
- Fix LicenseManager product type check in generateLicense()
- Add multiple order status hooks for reliable license generation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/License/LicenseManager.php

@@ -56,10 +56,15 @@ class LicenseManager
         }
 
         $product = wc_get_product($productId);
-        if (!$product instanceof LicensedProduct) {
+        if (!$product || !$product->is_type('licensed')) {
             return null;
         }
 
+        // Ensure we have the LicensedProduct instance for type hints
+        if (!$product instanceof LicensedProduct) {
+            $product = new LicensedProduct($productId);
+        }
+
         // Generate unique license key
         $licenseKey = $this->generateLicenseKey();
         while ($this->getLicenseByKey($licenseKey)) {