Add supercon tf wp shape types

[chris-ashe]

Description

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 70.96774% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.10%. Comparing base (d43ba2a) to head (59ac2a1).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
process/models/tfcoil/superconducting.py	61.90%	8 Missing ⚠️
process/core/init.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4194      +/-   ##
==========================================
+ Coverage   49.62%   52.10%   +2.47%     
==========================================
  Files         148      148              
  Lines       29969    30389     +420     
==========================================
+ Hits        14873    15835     +962     
+ Misses      15096    14554     -542     

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[Copilot]

Pull request overview

This PR introduces an explicit enum for superconducting TF winding-pack (WP) shape selection and starts using it in TF WP/case geometry logic and ripple calculations, replacing raw integer “magic values”.

Changes:

• Added SuperconductingTFWPShapeType (IntEnum) to represent WP shape types (rectangular, double rectangular, trapezoidal).
• Updated superconducting TF WP and case geometry branching to compare against enum members instead of integers.
• Updated build and init logic to use the enum for i_tf_wp_geom comparisons/default assignment.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
process/models/tfcoil/superconducting.py	Adds the WP shape enum and uses it in WP/case geometry branching.
process/models/build.py	Uses the new enum when selecting WP geometry-dependent parameters for ripple calculation.
process/core/init.py	Sets default i_tf_wp_geom using the new enum and updates a validation check to compare against the enum.

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[Copilot]

The switch on i_tf_wp_geom no longer has a final else branch. If i_tf_wp_geom is ever an unexpected value (e.g. the default -1 before check_process runs), none of the geometry/area variables will be assigned and the later area check/return will raise UnboundLocalError. Add an explicit fallback (e.g. raise ProcessValueError/ProcessValidationError with allowed values, or map unknown values to a default) to keep behavior safe and diagnosable.

[je-cook]

Please also do my previous review comments