[FIX] website_sale_aplicoop: payment-neutral label on the checkout button

The cart button that opens /eskaera/<slug>/checkout read "Proceed to
Checkout", and the curated eu/ca translations went further ("Ordaintzera
Joan", "Finalitza la Comanda"), all implying a payment step. With
instances running both with and without online payment, revert it to the
neutral "Review Order" in the source string, the JS labels and the es/eu/ca
translations.

Changing the msgid also drops the stale DB translation on update, so the
instance that still showed "Ir al pago" picks up the fresh term.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

website_sale_aplicoop/controllers/website_sale_i18n.py

@@ -100,7 +100,7 @@ def _get_translated_labels(self, lang=None, request_obj=None):
         ),
         "save_cart": tr("Save Cart"),
         "reload_cart": tr("Reload Cart"),
-        "proceed_to_checkout": tr("Proceed to Checkout"),
+        "proceed_to_checkout": tr("Review Order"),
         "confirm_order": tr("Confirm Order"),
         "back_to_cart": tr("Back to Cart"),
         "remove_item": tr("Remove Item"),