feat: Add Store Settings backend with full countries/timezones

✅ StoreSettingsProvider.php:
- get_countries() - All WooCommerce countries
- get_timezones() - All PHP timezones with UTC offsets
- get_currencies() - All WooCommerce currencies with symbols
- get_settings() - Current store settings
- save_settings() - Save store settings

✅ StoreController.php:
- GET /woonoow/v1/store/settings
- POST /woonoow/v1/store/settings
- GET /woonoow/v1/store/countries (200+ countries)
- GET /woonoow/v1/store/timezones (400+ timezones)
- GET /woonoow/v1/store/currencies (100+ currencies)
- Response caching (1 hour for static data)

🔌 Integration:
- Registered in Api/Routes.php
- Permission checks (manage_woocommerce)
- Error handling

Next: Update Store.tsx to use real API

includes/Api/Routes.php

@@ -8,6 +8,7 @@ use WooNooW\Api\OrdersController;
 use WooNooW\Api\AnalyticsController;
 use WooNooW\Api\AuthController;
 use WooNooW\API\PaymentsController;
+use WooNooW\API\StoreController;
 
 class Routes {
     public static function init() {
@@ -44,6 +45,10 @@ class Routes {
             // Payments controller
             $payments_controller = new PaymentsController();
             $payments_controller->register_routes();
+            
+            // Store controller
+            $store_controller = new StoreController();
+            $store_controller->register_routes();
         });
     }
 }