chore(backlog): 记录 g31 完成

.ua/backlog.json

@@ -610,8 +610,8 @@
       "title": "新增 tree 树形组件",
       "motivation": "文件树/组织架构/权限勾选等场景缺组件，只能手写嵌套 DOM，展开态与键盘可达性都要重造",
       "acceptance": "tree({ nodes, expanded, selected, defaultExpandAll, onSelect }) 递归渲染 + 箭头展开收起 + 点选 + Enter/→/← 键盘 + 禁用不响应；组件数 40→41 三处计数同步；npm run check 全绿",
-      "status": "open",
-      "notes": "自补：组件补充"
+      "status": "done",
+      "notes": "自补：组件补充；selected/expanded 信号均可外部受控"
     }
   ]
 }

.ua/iterations.log

@@ -75,3 +75,4 @@
 {"ts":"2026-10-26T11:38:48+08:00","id":"g28","result":"done","commit":"d9feeda","summary":"浮层 Esc 逐层关闭：menu/select/popover/tooltip/image 各自阻止冒泡，弹窗内的下拉收起不再连带关弹窗"}
 {"ts":"2026-10-26T11:40:10+08:00","id":"g29","result":"done","commit":"e5ed297","summary":"新增 carousel 轮播：横排位移 + 指示点/箭头/←→ 键 + autoplay 悬停暂停 + 环形回绕，组件数 39→40"}
 {"ts":"2026-10-26T11:41:05+08:00","id":"g30","result":"done","commit":"1a161d6","summary":"check 链加入 demo 构建，verify 新增产物锚点校验（负向删除锚点即失败）"}
+{"ts":"2026-10-26T11:42:29+08:00","id":"g31","result":"done","commit":"4b0dbfe","summary":"新增 tree 树形：递归节点 + 箭头展开收起 + 点选/Enter/→/← 键盘 + 禁用不响应，组件数 40→41"}