Add Simulation Data Serialization docs page for VTK export

[Copilot]

• Inspect current VTK serialization docs and current vector-field output
• Check repository test baseline (core tests currently fail before changes because the main environment is not instantiated: ACSets missing)
• Consult VTK/ParaView XML documentation and WriteVTK behavior for vector arrays
• Update the VTK docs example so the point-data section marks the flux array as the active vector field for ParaView
• Verify the generated .vtu XML contains both NumberOfComponents="3" on the flux DataArray and Vectors="flux" on PointData
• Re-run a focused local check for the serialization example
• Run parallel validation

[lukem12345]

@jpfairbanks If you have paraview installed locally still you could check this out

[lukem12345]

Checks out:

Screen.Recording.2026-04-18.at.2.14.55.PM.mov

[lukem12345]

The vector field was not immediately viewable in paraview, but that may be user error. The X Y and Z variables are all viewable.

[jpfairbanks]

Assuming the tests and docs build, this LGTM

[lukem12345]

I would want to hold off on merging until someone can check that the vector field data (the flux variable) is serialized appropriately.

paraview_data.zip