docs(sql): add external_target_code on biz_qc_work_order

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

docs/sql/2026-08-20-qc-work-order-external-target-code.sql

@@ -0,0 +1,5 @@
+-- 临时质检：外部质检对象编号（手写，可空）
+-- MySQL 5.7
+
+ALTER TABLE `biz_qc_work_order`
+  ADD COLUMN `external_target_code` varchar(64) DEFAULT NULL COMMENT '外部质检对象编号（手写）' AFTER `cell_product_id`;