fix: consolidate backend changes and fix icon imports

- Add standard .gitignore patterns (node_modules, .env, IDE files)
- Coupon.php: fix data structure for DataTable, add status filter
- Order.php: fix data structure to match OrderListItem expectations
- Product.php: add multi-currency prices array, unify nonce to 'formipay-admin'
- client.js: fix AJAX action names to match PHP (underscores → hyphens)
- OrderList.js: fix icon import (Icons.list), add response handling
- OrderListItem.js: fix icon import (Icons.seen)

src/admin/api/client.js

@@ -103,8 +103,8 @@ export const customersApi = {
  * Products API
  */
 export const productsApi = {
-    list: (params = {}) => ajaxRequest('formipay_tabledata_products', params),
-    get: (productId) => ajaxRequest('formipay_get_product', { post_id: productId }),
+    list: (params = {}) => ajaxRequest('formipay-tabledata-products', params),
+    get: (productId) => ajaxRequest('formipay-get-product', { post_id: productId }),
     getVariables: (productId) => ajaxRequest('get_product_variables', { post_id: productId }),
 };