🙏列的折叠展开

### 🏷 Version

| Package | Version |
| -------------- | ------- |
| @antv/s2 | 2.0.0 |
| @antv/s2-react | |
| @antv/s2-vue | |

### Sheet Type

- [ √] PivotSheet
- [ ] TableSheet
- [ ] GridAnalysisSheet
- [ ] StrategySheet
- [ ] EditableSheet

### 🖋 Description
列的数据也为树结构，不能折叠展开，切排版方向不能更改

### 🏞 What problem does this feature solve

解决列的数据层级过多导致列头过于庞大，改变排版方向，可自由折叠展开

### 🧐 Suggest the API

| name | type | default | description |
| ---- | ---- | ------- | ----------- |
| - | - | - | - |

No implementation files, tests, or entry points are identified. Start by reviewing the PivotSheet column-tree behavior and existing layout APIs, then clarify the collapse/expand interaction, layout-direction requirements, and proposed API. Done should include an agreed design, implemented column hierarchy controls, and coverage for the resulting header layout.

Written by the indexing model from the issue text.