Update Polish translations and enhance checkout styles

- Changed the button text for adding a voucher code to Polish ("Dodaj kod rabatowy").
- Updated placeholder text in checkout form fields to use field labels.
- Modified shipping template to display shipping time in Polish.
- Refined CSS styles for better layout and responsiveness in checkout areas.
- Updated custom CSS version in the head template and added a script to move the free shipping message to the top of the container.

modules/thecheckout/views/templates/front/_partials/cart-voucher.tpl

@@ -54,7 +54,7 @@
               <input type="hidden" name="addDiscount" value="1">
               <div class="promo-input-button d-f">
                 <input class="promo-input" type="text" name="discount_name" placeholder="{l s='Promo code' d='Shop.Theme.Checkout'}">
-                <button data-link-action="x-add-voucher" type="submit" class="btn btn-primary"><span>{l s='Add' d='Shop.Theme.Actions'}</span></button>
+                <button data-link-action="x-add-voucher" type="submit" class="btn btn-primary"><span>Dodaj kod rabatowy</span></button>
               </div>
             </form>
           {/block}