iter(g31): 新增 tree 树形组件

apps/demo/main.ts

@@ -27,6 +27,7 @@ import {
   inputNumber,
   list,
   carousel,
+  tree,
   menu,
   modal,
   pagination,
@@ -176,6 +177,7 @@ const tableLoading = signal(false);
 const menuPick = signal('');
 const listPick = signal(''); // 列表点击选中的条目标题
 const slideIndex = signal(0); // 轮播当前下标（外部受控演示）
+const treePick = signal('core'); // 树形选中节点 key
 
 // —— 禁用态演示：开关信号同时绑定 switch 的 checked 与 checkbox 的 disabled ——
 const locked = signal(true);
@@ -619,6 +621,28 @@ const content = h(
       h('span', { class: 'out' }, () => `第 ${slideIndex() + 1} / 3 张`),
     ),
   ),
+  section(
+    'sec-tree',
+    '树形',
+    'tree：递归节点，箭头展开/收起、点标签选中；键盘 Enter 选中、→ 展开、← 收起，禁用节点不响应。',
+    h(
+      'div',
+      { class: 'row' },
+      tree({
+        nodes: [
+          { key: 'src', label: 'src', children: [
+            { key: 'core', label: 'core', children: [{ key: 'frame', label: 'frame' }, { key: 'table', label: 'table-core' }] },
+            { key: 'skin', label: 'skin', children: [{ key: 'ui', label: 'ui' }, { key: 'css', label: 'ui.css' }] },
+          ] },
+          { key: 'apps', label: 'apps', children: [{ key: 'demo', label: 'demo' }, { key: 'docs', label: 'docs' }] },
+          { key: 'lock', label: 'package-lock.json（禁用示例）', disabled: true },
+        ],
+        selected: treePick,
+        onSelect: (n) => treePick(n.key),
+      }),
+      h('span', { class: 'out' }, () => (treePick() ? `已选节点：${treePick()}` : '未选中节点')),
+    ),
+  ),
   section(
     'sec-menu',
     '下拉菜单',