When user has no dataset, don't display button to download statistics

When user has no published dataset, don't display button to download statistics.

(currently when downloading monthly stats, it downloads an empty CSV file; and when downloading teh catalog it shows a 404)

<img width="1217" height="480" alt="Image" src="https://github.com/user-attachments/assets/4b103c19-d16d-4d90-a013-00fc038bcf34" />