User datasets workspace: the toggle for listing datasets from all projects is hidden when the user has no datasets for the current project.

With 1 dataset in plasmo and 1 in mbio:
<img width="877" height="285" alt="Image" src="https://github.com/user-attachments/assets/b8b942e3-a489-498e-8b01-c8c89c6a836b" />

With no dataset in plasmo and 1 in mbio:
<img width="862" height="308" alt="Image" src="https://github.com/user-attachments/assets/aa3e35d6-ade5-44e9-bcf4-e64cdd2de8f5" />