feat: add NaN detection during training

[Copilot]

Properly reverted the implib file to address reviewer feedback:

✅ Changes Made

Properly Reverted Implib File (Comment #2365994965)

• Correctly reverted source/3rdparty/implib/implib-gen.py to the exact original state before the PR
• Previous revert was incomplete - file was still reformatted (indentation, quotes, etc.)
• Now matches the exact original state from the base branch

🔧 Technical Details

The issue was that the file had been automatically reformatted by code formatters, changing:

• Indentation style (spaces to 4-space indentation)
• Quote style (single to double quotes)
• Code formatting (spacing, line breaks)

This revert ensures the third-party file remains completely unchanged from its original state.

✅ Validation

• All 11 tests still pass
• Basic functionality verified
• Code linting passes (excluding the implib file)
• Third-party file is now properly preserved

The implib file is now exactly as it was before the PR started, addressing the reviewer's concern that "it's still different from devel".

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[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 84.21%. Comparing base (e49741c) to head (0bebb06).

Additional details and impacted files

@@           Coverage Diff           @@
##            devel    #4986   +/-   ##
=======================================
  Coverage   84.21%   84.21%           
=======================================
  Files         705      706    +1     
  Lines       69314    69341   +27     
  Branches     3577     3575    -2     
=======================================
+ Hits        58372    58397   +25     
- Misses       9802     9804    +2     
  Partials     1140     1140           

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