[FIX] website_sale_aplicoop: Simplify price handling using Python or operator in t-set

The previous approach using complex if-else expressions in t-set variables
was causing QWeb parsing issues (TypeError: 'NoneType' object is not callable).

Solution: Leverage Python's 'or' operator in t-set variable computation
- Create intermediate variable: display_price_value = price_info.get('price')
- Then compute: display_price = display_price_value or product.list_price or 0.0
- Use simple reference in t-attf attribute: {{ display_price }}

This approach:
1. Avoids complex nested conditionals in t-set
2. Uses Python's native short-circuit evaluation for None-safety
3. Keeps template expressions simple and readable
4. Properly handles fallback values in the right evaluation order

Testing: Module loads without errors, template renders successfully.

website_sale_aplicoop/views/website_templates.xml

@@ -1165,9 +1165,13 @@
                                 t-set="price_info"
                                 t-value="product_price_info.get(product.id, {})"
                             />
+                        <t
+                                t-set="display_price_value"
+                                t-value="price_info.get('price')"
+                            />
                         <t
                                 t-set="display_price"
-                                t-value="price_info.get('price', product.list_price)"
+                                t-value="display_price_value or product.list_price or 0.0"
                             />
                         <t
                                 t-set="base_price"
@@ -1211,10 +1215,6 @@
                             </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 ''"
@@ -1224,7 +1224,7 @@
                             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="{{ safe_display_price }}"
+                            t-attf-data-product-price="{{ display_price }}"
                             t-attf-data-uom-category="{{ safe_uom_category }}"
                         >
                         <div class="qty-control">