Add baby-step giant-step discrete logarithm algorithm

[felipeofdev-ai]

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• 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.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword.

Summary

Adds maths/baby_step_giant_step.py implementing the classic baby-step giant-step method for discrete logarithms modulo a prime (or any modulus where base is invertible).

• Builds a baby-step table of size ⌈√(modulus-1)⌉
• Uses modular inverse giant steps via pow(base, -m, modulus)
• Returns the smallest non-negative exponent; raises ValueError when no solution exists
• Doctests verified locally with python -m doctest

Reference: https://en.wikipedia.org/wiki/Baby-step_giant-step

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— Felipe Fernandes · Systems & Agentic AI Engineer
https://github.com/felipeofdev-ai · https://felipeofdev-ai.github.io/

[felipeofdev-ai]

Thanks for reviewing — CI is green on my side. Happy to adjust anything you need.

— Felipe Fernandes · Systems & Agentic AI Engineer
https://github.com/felipeofdev-ai · https://felipeofdev-ai.github.io/