added normal vector update to pair iterative solver

[gavinwhetstone]

Description

Type of change

Please select all relevant options

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Formatting and/or style fixes
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Test A :
• Test B :

Test Configuration:

• OS version: Sequoia 15.7.5
• Hardware: Apple M2 Max
• Compiler: Clang 19.1.7

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• The code builds from scratch with my new changes
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules