feat(pl): add notes column on transport address library

Persist address-level precautions for later fill into plan load/delivery notes.

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

docs/sql/migrations/2026-09-02-pl-transport-address-notes.sql

@@ -0,0 +1,7 @@
+-- 运输地址库增加注意事项
+-- 设计: docs/superpowers/specs/2026-09-02-pl-transport-address-notes-fill-design.md
+
+SET NAMES utf8mb4;
+
+ALTER TABLE `pl_transport_address`
+  ADD COLUMN `notes` varchar(500) DEFAULT NULL COMMENT '注意事项' AFTER `contact_phone`;