when the `y` position of the entire scene changes, the camera in Viewer mode remains at the same level

[Algorush]

This is important because there may be situations where the elevation is slightly out of line with 3DStreet. I think we can now fix this by setting the y value for the Viewer camera when changing the y position for the scene. But later it is better to use navigation-mesh. Aframe-inspector has an option to calculate nav-mesh