Handle zero and negative inputs in least common multiple implementations

[Tithi234]

Describe your change:

• Handles zero input cases correctly for LCM
• Ensures LCM results are always non-negative
• Improves correctness without changing existing algorithm structure

What type of change is this?

• Fix a bug or typo in an existing algorithm?

Checklist:

• I have read CONTRIBUTING.md
• This pull request is all my own work
• I know that pull requests will not be merged if they fail the automated tests
• This PR only changes one algorithm file
• All functions and variable names follow Python naming conventions
• All function parameters and return values are annotated with Python type hints
• All functions have doctests that pass the automated testing

[Tithi234]

Thanks for the review and automated checks.

I’m closing this PR to avoid confusion as the current CI checks are failing.
I’ll take time to fix the issues properly and open a clean follow-up PR
that fully follows the contribution guidelines.

Appreciate the maintainers’ work!