FPC5/6 SEC filing refinements

[softwareengineerprogrammer]

FPC5 refinements derived from https://www.sec.gov/Archives/edgar/data/1853868/000162828026025821/exhibit991-sx1.htm

1. Addresses FPC5 Utilization factor tweak NatLabRockies/GEOPHIRES-X#498
2. Cite 85°C injection temperature
3. Cite/compare 19.5% Heat to Power Conversion Efficiency with 13.9% result

Testing & Verification

1. Unit tests added: N/A
2. Unit tests updated:
   1. Fervo_Project_Cape-5
   2. Fervo_Project_Cape-6
3. Manual testing:
   1. Manually verified/self-reviewed
   2. Verified docs build locally
   3. 🚧 Web interface

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Change Checklist

Observe the following checklist items before and after merging, as applicable.

Before merging:

1. I certify that I am a human and I have manually verified the correctness of the changes in this PR.
2. Add a CHANGELOG entry if your change includes a new version Too minor for version bump

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Self-reviewed in #171