Optimize I25norm.F: eliminate code duplication and improve arithmetic efficiency

[Copilot]

Description of the feature or the bug

The I25norm.F file contained substantial code duplication and inefficient arithmetic patterns affecting performance in interface type 25 (edge-to-edge contact) computations.

Description of the changes

Code Consolidation (I25TAGN subroutine)

• Merged duplicate FLAGREMN conditional blocks (~140 lines) into unified loops with internal conditionals
• Consolidated redundant edge processing sections that were computing the same operations twice
• Reduced from separate IF/ELSE paths to single loop with conditional logic

Arithmetic Optimization (I25NORMP, I25ASSNP subroutines)

• Split normalization operations for better instruction scheduling:

! Before: nested operations prevent optimization
AAA=RUN/MAX(REM30,SQRT(XN1(I)*XN1(I)+YN1(I)*YN1(I)+ZN1(I)*ZN1(I)))

! After: separated dot product enables better pipelining
AAA=XN1(I)*XN1(I)+YN1(I)*YN1(I)+ZN1(I)*ZN1(I)
AAA=RUN/MAX(REM30,SQRT(AAA))

Impact

• Net reduction: 91 insertions, 136 deletions (-45 lines)
• Enhanced compiler vectorization opportunities
• Improved instruction cache utilization
• Single code paths improve maintainability

All algorithm logic preserved exactly; changes are purely structural optimizations.

Original prompt

I would like to optimize the file I25norm.F.
Let's focus on performance.

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