Viewer: controlling the time has no effect.

[iSach]

Describe the bug
The Time slider in the new viewer (viser) does not change the time of the rendered image.

Furthermore, it is impossible to render dynamic scenes in the new viewer. Unlike the legacy one, there is no per-keyframe time setting.

To Reproduce

1. Train a dynamic model (e.g., K-Planes).
2. During training, or afterward with ns-viewer, check the viser viewer.
3. At the bottom of the Control panel, try to change the Time slider.
4. Rendered image does not change.

Expected behavior
The updated time should correctly be fed to the network. Maybe a separate issue can be opened for addressing the lack of time controls in the Render panel.