feat: 去掉商品取货码，管理员可直接发货完成

已付款订单不再生成或核验取货码，管理员确认后即可完成订单。

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/server/prisma/migrations/20260925111500_drop_product_order_pickup_code/migration.sql

@@ -0,0 +1,3 @@
+-- Paid product orders are fulfilled directly by an administrator.
+-- The pickup code is no longer generated, shown, or required.
+ALTER TABLE `product_orders` DROP COLUMN `pickup_code`;