Add pressure peaking fraction value

[chris-ashe]

This pull request introduces several enhancements to how plasma pressure and temperature profiles are calculated, stored, and reported, particularly improving the handling of pedestal profile cases. The main changes include adding new derived quantities (such as central-to-volume-averaged ratios), calculating and outputting pedestal and separatrix pressures, and updating the summary plots and output files to reflect these new metrics.

Enhancements to plasma profile calculations:

• Added calculation and storage of the ratio of central to volume-averaged plasma electron temperature (f_temp_plasma_electron_on_axis_vol_avg) and plasma thermal pressure (f_pres_plasma_thermal_on_axis_vol_avg). These are now computed in both parabolic and pedestal parameterisations, and in the profile factors calculation.

• For pedestal profile cases, the code now calculates and stores the plasma thermal pressure at the pedestal (pres_plasma_pedestal_thermal) and at the separatrix (pres_plasma_separatrix_thermal).
  Output and reporting improvements:

• The output file generation now includes the new ratio quantities and, for pedestal profiles, the pedestal and separatrix pressures.

• 🐛 Fixed units in the output for plasma thermal energies from [W] to [J] for clarity and correctness.

Plotting and summary display updates:

• The plasma summary plots now display the new ratios and, when appropriate, show pedestal and separatrix pressures in the plot annotations.

Codebase and import updates:

• Added necessary imports for PlasmaProfileShapeType to support the new logic for pedestal profile handling.

These changes improve the physical fidelity and reporting of plasma profile data, especially for cases with pedestal structure, and enhance the usability of the output for analysis and validation.## 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 62.16216% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.72%. Comparing base (83d9f63) to head (542e0ed).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
process/core/io/plot/summary.py	0.00%	7 Missing ⚠️
process/models/physics/physics.py	0.00%	6 Missing ⚠️
process/models/physics/plasma_profiles.py	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4483      +/-   ##
==========================================
+ Coverage   48.67%   48.72%   +0.04%     
==========================================
  Files         151      151              
  Lines       29734    29778      +44     
==========================================
+ Hits        14474    14508      +34     
- Misses      15260    15270      +10     

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