iter: d17 表单错误态覆盖包裹式控件 + 校验时机事件

apps/demo/main.ts

@@ -268,10 +268,11 @@ const content = h(
     '表单校验',
     'form + formItem：必填 / 长度 / 正则校验，全部通过才触发提交；失焦校验、输入清错。',
     form(
-      { submitText: '注册', onSubmit: () => formResult(`提交成功：${username()} / ${email()}`) },
+      { submitText: '注册', onSubmit: () => formResult(`提交成功：${username()} / ${email()} / ${city()}`) },
       [
         formItem({ label: '用户名', required: true, value: username, rules: [{ min: 2, max: 12, message: '用户名需 2-12 个字符' }] }, textField({ placeholder: '2-12 个字符', value: username })),
         formItem({ label: '邮箱', required: true, value: email, rules: [{ pattern: /^[\w.-]+@[\w-]+\.[\w.]+$/, message: '邮箱格式不正确' }] }, textField({ placeholder: 'you@example.com', value: email })),
+        formItem({ label: '城市', required: true, value: city }, select({ options: cities.map((c) => ({ value: c, label: c })), value: city, placeholder: '请选择城市…' })),
       ],
     ),
     h('span', { class: 'out' }, () => formResult() || '等待提交…'),