[Infra/website] Add analytics for fluss.apache.org

### Search before asking

- [x] I searched in the [issues](https://github.com/apache/fluss/issues) and found nothing similar.

### Description

ASF provides analytics tools like

- https://privacy.apache.org/matomo/
- https://analytics.apache.org/

to track website infrastructure. By measuring traffic, usage patterns, and performance, these insights will help us identify what’s working, spot gaps, and plan future features and improvements.

### Willingness to contribute

- [x] I'm willing to submit a PR!