feat: Add licensing module backend

- LicensingSettings.php with key format, activation limits, expiry settings
- LicenseManager.php with key generation, activation/deactivation, validation
- LicensingModule.php with WooCommerce product meta integration
- LicensesController.php with admin, customer, and public API endpoints
- Database tables: woonoow_licenses, woonoow_license_activations
- has_settings enabled in ModuleRegistry

includes/Core/ModuleRegistry.php

@@ -82,6 +82,7 @@ class ModuleRegistry {
                 'category' => 'products',
                 'icon' => 'key',
                 'default_enabled' => false,
+                'has_settings' => true,
                 'features' => [
                     __('License key generation', 'woonoow'),
                     __('Activation management', 'woonoow'),