📏 Tf plasma offset plot proc

[chris-ashe]

This pull request standardizes and clarifies variable naming related to the vertical and radial build of the toroidal field (TF) coil, updates documentation and input handling, and improves visualization in the plotting routines. The most significant changes are the renaming of key variables for consistency and clarity, updates to documentation and input files, and enhancements to the coil structure plot.

🔄 Variable renaming

• tfoffset to dz_tf_plasma_centre_offset
• Renamed tfootfi to f_dr_tf_outboard_inboard for the outboard/inboard TF coil thickness ratio,

Documentation and input/output updates:

• Updated documentation in tf-coil.md to reflect new variable names and descriptions for user input parameters.
• Updated input variable registration and obsolete variable mapping to use the new names.
• Updated all example output data files to use the new variable names for TF coil vertical offset.

Plotting improvements:

• Enhanced plot_tf_coil_structure in plot_proc.py by adding markers for the top and vertical center of the coil, a horizontal line at the coil center, and a label showing the offset between the coil center and plasma center for better visualization and clarity.

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 45.45455% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.06%. Comparing base (4818b3b) to head (30f200a).

Files with missing lines	Patch %	Lines
process/io/plot_proc.py	0.00%	3 Missing ⚠️
process/build.py	0.00%	2 Missing ⚠️
process/stellarator.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3941      +/-   ##
==========================================
- Coverage   46.06%   46.06%   -0.01%     
==========================================
  Files         123      123              
  Lines       28467    28470       +3     
==========================================
  Hits        13114    13114              
- Misses      15353    15356       +3     

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[j-a-foster]

Happy with changes.

[clmould]

These labels are not being included in the legend?

[chris-ashe]

Just realised the legend is using the defined labels array to show the arc points. When I add the coil masses and areas section beside the plot in a (121) config I will put it into a real text box