Add to_standard_orientation for SurfaceRZFourier

[scadena-pf]

Summary

• Adds to_standard_orientation() to normalize the poloidal angle parametrization of stellarator-symmetric SurfaceRZFourier surfaces so that theta=0 is on the outboard side and theta increases counterclockwise in an R-Z cross-section.
• Reuses existing evaluate_points_rz and _evaluate_dz_dtheta to detect the current orientation, then applies Fourier coefficient transformations as needed.
• Includes 4 test cases covering all orientation combinations (external/internal × ccw/cw), each verifying geometric equivalence via evaluate_points_xyz.
• This function was already referenced (but missing) in the from_points docstring.

Details

Five new functions added to surface_rz_fourier.py:

Function	Purpose
_is_theta_external	Checks if theta=0 is on the outboard side
_is_theta_counterclockwise	Checks if theta increases CCW in R-Z plane
_surface_shift_theta_by_pi	Shifts theta origin by multiplying coefficients by (-1)^m
_surface_change_theta_sign	Reverses theta direction by flipping toroidal mode arrays
to_standard_orientation	Public entry point combining the above

Test plan

• 4 new tests covering all orientation combinations pass
• All 55 existing + new tests pass
• ruff, black, isort all clean

🤖 Generated with Claude Code

[graphite-app]

Merge activity

• Feb 11, 8:22 AM UTC: scadena-pf added this pull request to the Graphite merge queue.
• Feb 11, 8:23 AM UTC: The Graphite merge queue couldn't merge this PR because it failed for an unknown reason (Fast-forward merges are not supported for forked repositories. Please create a branch in the target repository in order to merge).
• Feb 11, 8:49 AM UTC: scadena-pf added this pull request to the Graphite merge queue.
• Feb 11, 8:51 AM UTC: The Graphite merge queue couldn't merge this PR because it failed for an unknown reason (Fast-forward merges are not supported for forked repositories. Please create a branch in the target repository in order to merge).