Add dipole magnetic vector potential calcs

[mdavids-cfs]

• Add dipole magnetic vector potential calcs (rust)
• Unit tests in rust
• Unit tests in python

[jlogan-cfs]

3.0.0 2025-10-29

Added

• Rust
  • Add methods for vector potential of a dipole in physics::point_source and python.rs bindings
  • Add physics::volumetric module with methods for fields inside a uniformly magnetized sphere
  • Add math::{clip_nan, switch_float} functions for branchless-in-assembly float selection operations
• Python
  • Add vector_potential_dipole function
  • Add optional sphere radius input for dipole flux density

Changed

• Rust
  • !Require sphere radius input for dipole flux density
  • Update dependencies
  • Use more codegen units and don't do LTO for debug builds
  • Use more mul_add in flux_circular_filament
  • Use multiplication instead of pow in dipole calcs
• Python
  • !Enable more instruction sets for x86 processors
  • Replace flatten() with ravel() everywhere to reduce copies

[mdavids-cfs]

Looking good!

[mdavids-cfs]

FYI, I changed
from . import test_funcs as _test
to
from test import test_funcs as _test

while I was testing it, so I could run some tests in the debugger

[mdavids-cfs]

This is wizardry!