Handle appended rows in presolve (parallel rows reduction)

[fwesselm]

Description

• Parallel rows and columns detection now removes the cut row (not the non-cut row) when two parallel rows have different row types. This prevents loss of original constraints when moveCutsToPool later moves cuts to the cut pool. Note that this change is needed when presolve is performed after a restart (including cuts) and rows are appended (e.g., Fourier-Motzkin reduction).
• Replaced manual isOrigRow/isOrigCol/isCutRow loops across MIP code with new utility methods (getOrigRows(), getOrigCols(), getCutRows(), getNonCutRows()) on HighsPostsolveStack.
• Don't perform intial sweep if options->presolve_rule_test is set.
• Added a unit test.
• Ran 100 MIPs to verify that code changes do not affect behavior.

Checklist

• I have read the contributing guidelines
• This PR targets the latest branch
• Tests are passing
• Documentation was updated where relevant
• This PR is not primarily AI-generated (per the AI contributions policy in CONTRIBUTING.md)

[codecov]

Codecov Report

❌ Patch coverage is 98.07692% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.25%. Comparing base (f1de972) to head (a47ac64).
⚠️ Report is 923 commits behind head on latest.

Files with missing lines	Patch %	Lines
highs/presolve/HPresolve.cpp	96.55%	2 Missing ⚠️
check/TestPresolveRules.cpp	98.46%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #3250      +/-   ##
==========================================
+ Coverage   73.16%   73.25%   +0.08%     
==========================================
  Files         430      445      +15     
  Lines      103967   108121    +4154     
  Branches    16719    17333     +614     
==========================================
+ Hits        76067    79199    +3132     
- Misses      27624    28646    +1022     
  Partials      276      276              

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[Opt-Mucca]

A very nice find with a very simple fix!