[FXC-4893] feat(): augment MeshingParams docstring with refinement_factor and gap_treatment_strength

[benflexcompute]

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Note

Low Risk
Low risk because the PR only changes a docstring/example and does not affect meshing logic or parameter validation.

Overview
Updates the MeshingParams docstring example in meshing_param/params.py to explicitly include the refinement_factor and gap_treatment_strength arguments when constructing fl.MeshingParams.

No runtime behavior or validation changes are introduced; this is documentation-only.

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