[FIX] website_sale_aplicoop: Replace or operators with t-set safe variables in QWeb template

The eskaera_shop_products template was using 'or' operators directly in
t-attf-* attributes, which causes QWeb parsing issues when values are None.

Solution: Pre-compute safe variable values using t-set before the form element
- safe_display_price: Handles None values for display_price, falls back to product.list_price, then 0
- safe_uom_category: Safely checks product.uom_id and category_id chain before accessing name

This pattern is more QWeb-compatible and avoids inline operator evaluation issues
that were causing "TypeError: 'NoneType' object is not callable" errors.

Tested: Template loads successfully, safe variables render correctly.

website_sale_aplicoop/views/website_templates.xml

@@ -1211,13 +1211,21 @@
                             </p>
                         </t>
                     </div>
+                    <t
+                            t-set="safe_display_price"
+                            t-value="display_price if display_price else (product.list_price if product.list_price else 0)"
+                        />
+                    <t
+                            t-set="safe_uom_category"
+                            t-value="product.uom_id.category_id.name if (product.uom_id and product.uom_id.category_id) else ''"
+                        />
                     <form
                             class="add-to-cart-form"
                             t-attf-data-order-id="{{ group_order.id if 'group_order' in locals() else '' }}"
                             t-attf-data-product-id="{{ product.id }}"
                             t-attf-data-product-name="{{ product.name }}"
-                            t-attf-data-product-price="{{ display_price or product.list_price or 0 }}"
+                            t-attf-data-product-price="{{ safe_display_price }}"
-                            t-attf-data-uom-category="{{ product.uom_id.category_id.name if product.uom_id.category_id else '' }}"
+                            t-attf-data-uom-category="{{ safe_uom_category }}"
                         >
                         <div class="qty-control">
                             <label