feat: add inline catalog checkout with modals

Replace redirect to /comprar with a 2-step modal flow (cart confirmation
+ personal data) on the catalog page. Add createCatalogPurchase API
endpoint for catalog sales.

src/services/django-api.js

@@ -60,6 +60,11 @@ class DjangoApi {
         return this.postRequest(url, purchase);
     }
 
+    createCatalogPurchase(purchase) {
+        const url = this.base + "/don_confiao/api/catalog_sales/";
+        return this.postRequest(url, purchase);
+    }
+
     createReconciliationJar(reconciliation) {
         const url = this.base + "/don_confiao/reconciliate_jar";
         return this.postRequest(url, reconciliation);