[Bug] 表头设置二级时，columns找不到类型

Version

1.20.0

Link to Minimal Reproduction

https://codesandbox.io/p/sandbox/vtable-list-table-forked-8dzz22?file=%2Fsrc%2Findex.ts%3A136%2C17

Steps to Reproduce

import { ColumnsDefine } from "@visactor/vtable";
const columnsList: ColumnsDefine = [
  {
    field: "id",
    title: "ID",
    width: 80,
    sort: true,
  },
  {
    field: "full name",
    title: "Full name",
    columns: [
      {
        field: "name",
        title: "First Name\n(input editor)",
        width: 120,
        editor: "input-editor",
      },
      {
        field: "lastName",
        title: "Last Name\n(input editor)",
        width: 100,
      },
    ],
  },
  {
    field: "sex",
    title: "sex\n(list editor)",
    width: 100,
  }
}

Current Behavior

二级表头的columns类型无法推导出来（为undefined），貌似还有很多类似情况，是否是类型未定义完整

Expected Behavior

希望能够提供完整可使用的类型

Environment

- OS:
- Browser:
- Framework:

Any additional comments?

No response

Start with the TypeScript reproduction in src/index.ts at the linked CodeSandbox location and inspect the exported ColumnsDefine type used by the nested columns property. Verify the type definitions for both header levels and confirm in the reproduction that nested columns receive usable inferred types rather than undefined.