Add safety seal support to orders and related logic for wash certificates

- Introduced `safety_seal` column in the `orders` table.
- Updated order creation and completion logic to handle safety seal values.
- Enhanced order and booking classes to manage safety seal attachment and retrieval.
- Added tests to validate safety seal functionality in order processing.

services/nginx/app/classes/orders_schema_bootstrap.php

@@ -26,6 +26,11 @@ class orders_schema_bootstrap
                 ADD COLUMN IF NOT EXISTS include_in_invoice TINYINT(1) NULL DEFAULT NULL
                 AFTER created_at"
         );
+        $db->query(
+            "ALTER TABLE orders
+                ADD COLUMN IF NOT EXISTS safety_seal VARCHAR(255) NULL DEFAULT NULL
+                AFTER po"
+        );
 
         self::$initialized = true;
     }