Ability to temporarily disable node markers and clusters.

I was attempting to find liberland east of Croatia and west of Serbia but I'm having trouble because Europe is so densely packed with nodes that you can't see city names due to all the markers and clusters.

<img width="1080" height="2400" alt="Image" src="https://github.com/user-attachments/assets/b094ae6f-7df3-4c4a-b94c-12a86d1d4b0f" />