Add R1 light-current lensing operators

[gpartin]

Summary

• Adds package-native 19-point spectral/equilibrium helpers for chi lens setup.
• Adds R1 light-current packet, vacuum-subtracted potential, acceleration, and leapfrog step helpers.
• Adds Noether spatial-current readouts used by the lensing reproduction pack.
• Bumps lfm-physics to 1.4.3 and updates the stale pre-commit mypy hook pin.

Validation

• pre-commit run on changed files
• python -m pytest -m "not slow" --timeout=120 -q
• python -m build
• C:\Papers.venv\Scripts\python.exe -X utf8 -u C:\Papers\paper_experiments\lfm_light_chi_coupling_probe\run_full_r1_complex_probe.py

Notes

The v1.4.2 tag already existed on GitHub and points at an older 27-point stencil commit, while PyPI still has 1.4.1 as latest. This release therefore uses v1.4.3.

[Copilot]

Pull request overview

Adds new Level-1 “R1 light-current lensing” operators and accompanying analysis/initial-condition helpers, alongside 19-point-stencil-consistent Poisson/equilibrium utilities. This extends lfm’s package-native toolset for lensing reproduction workflows while keeping the numerical operators consistent with the existing 19-pt evolution stencil.

Changes:

• Add a 19-point-stencil spectral symbol (eigenvalue_19pt) plus FFT Poisson/equilibrium helpers consistent with laplacian_19pt.
• Add R1 light packet initialization + vacuum-subtracted potential + acceleration + leapfrog step helpers.
• Add spatial Noether current readouts (raw and positive-clipped), update exports, tests, and bump version to 1.4.3.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/test_stencils.py	Adds a Fourier-mode consistency test for eigenvalue_19pt vs laplacian_19pt.
tests/test_physics_modules.py	Adds tests for spatial Noether current and positive-clipped current.
tests/test_fields.py	Adds tests for 19-pt Poisson roundtrip, 19-pt chi equilibrium, and R1 light helpers; updates public import checks.
pyproject.toml	Bumps package version to 1.4.3.
lfm/fields/light.py	Implements planar R1 packet constructor, vacuum-subtracted potential, acceleration, and leapfrog step.
lfm/fields/equilibrium.py	Implements poisson_solve_fft_19pt, equilibrate_chi_19pt, and equilibrate_from_fields_19pt; refines dtype handling in multicolor path.
lfm/fields/init.py	Re-exports new equilibrium + light helpers and updates __all__.
lfm/experiment/collision.py	Minor numeric cleanup to ensure eigenvalue is a Python float.
lfm/core/stencils.py	Adds eigenvalue_19pt matching the 19-point Laplacian stencil.
lfm/core/init.py	Re-exports eigenvalue_19pt and laplacian_19pt from lfm.core.
lfm/analysis/phase.py	Adds spatial Noether current helpers.
lfm/analysis/init.py	Re-exports Noether current helpers.
lfm/init.py	Bumps __version__ to 1.4.3 and re-exports new helpers at top-level.
CHANGELOG.md	Adds 1.4.3 changelog entry documenting newly added helpers.
.pre-commit-config.yaml	Updates the pinned mypy mirror revision.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.