Add getOrderItemObjects and getProduct methods, and enhance Slack notifications in invoicing routes

- Introduce `getOrderItemObjects` in `orders_o` to retrieve item objects for an order.
- Add `getProduct` in `order_items_o` for product retrieval by item.
- Enhance Slack notification logic in invoicing routes for better error reporting and fixed pricing summaries.
- Temporarily comment out permission checks in certain invoicing endpoints for debugging purposes.

services/nginx/app/objects/order_items_o.php

@@ -339,4 +339,12 @@ class order_items_o extends db
         }
         return $items;
     }
+
+    /**
+     * @throws Exception
+     */
+    public function getProduct(): products_o
+    {
+        return (new products_o())->select((int)$this->product_id->value());
+    }
 }

services/nginx/app/objects/orders_o.php

@@ -1549,4 +1549,21 @@ class orders_o extends db
         $row = $result->fetch_assoc();
         return (int)$row['wash_count'];
     }
+
+    /**
+     * @throws Exception
+     * @retuns order_items_o[]
+     */
+    public function getOrderItemObjects(): array
+    {
+        self::requireSelected();
+        $order_items = $this->getOrderItems((int)$this->id);
+        $order_item_objects = [];
+        foreach ( $order_items as $item ) {
+            $order_item = new order_items_o();
+            $order_item->select((int)$item['id']);
+            $order_item_objects[] = $order_item;
+        }
+        return $order_item_objects;
+    }
 }