[FEATURE REQUEST]Lay out categories horizontally using a row container

After serveral rounds of discussion on how to reconstruct CNCF CNAI landscape to AI Native landscape, the community now almost reach consensus to lay out categories horizontally using a row container, slack links could be found at [1][2][3][4].

The draft AI Native landscape layout could be found here:
> https://ai-native-landscape-preview.netlify.app/?group=ai-native-proposed
> or
> http://43.165.7.70:12000/?group=ai-native (if the above link become invalid)

there are three rows in the draft AI Native group landscape, refer to the following list. In the second row, there are three categories, data, training and inference; and each category contains multiple sub-categories:
- [AI Agent]
- [Data, Training, Inference]
- [AI Native Infra]

Currently landscape2 only supports laying out categories vertically, so the feature request is proposed.

The refererence implemention of rows is to configure the row layout in the **settings.yml** as following:

```
groups:
- name: Projects and products
alias: projects
...
- name: AI Native (proposed)
alias: ai-native-proposed
categories:
- AI Agent
- Inference
- Training
- Data
- AI Native Infra
category_rows:
- [AI Agent]
- [Data, Training, Inference]
- [AI Native Infra]
```

Reference:
[1] CNCF AI TCG channel: https://cloud-native.slack.com/archives/C08Q78J65A7/p1775118381260299
[2] CNCF AI TCG channel: https://cloud-native.slack.com/archives/C08Q78J65A7/p1772614288421669
[3] CNCF Landscapers channel: https://cloud-native.slack.com/archives/CM09QERF1/p1773198799247499
[4] CNCF Landscapers channel: https://cloud-native.slack.com/archives/CM09QERF1/p1774949382211369