📝 docs(stories): rename and update cart UI refactor story

- rename file from 001.12.cart-ui-refactor.story.md to 001.012.cart-ui-refactor.story.md for consistent numbering
- update story status from Draft to Done
- correct story number in title from 001.12 to 001.012

docs/stories/001.12.cart-ui-refactor.story.md → docs/stories/001.012.cart-ui-refactor.story.md

@@ -1,7 +1,7 @@
-# Story 001.12: 购物车页面UI重构
+# Story 001.012: 购物车页面UI重构
 
 ## Status
-Draft
+Done
 
 ## Story
 **As a** 小程序用户，