1. Please load the dataset from "QMCPACK/data/QMCPACK.vti".

2. Compute the critical points of the scalar field.

3. Save the critical points as "QMCPACK/results/{agent_mode}/QMCPACK.vtk" in legacy VTK format.
    - The output should contain the critical points as point data
    - Include an array called "CriticalType" that labels each point according to what type of critical type it is. Use the following convention:
    * 0 for minima
    * 1 for 1-saddles
    * 2 for 2-saddles  
    * 3 for maxima
    * 4 for degenerate critical points
    - The point coordinates should be in index space (grid coordinates), not world coordinates