Performance: Limit or filter revwalk for large repos

[Alex-Grimes]

Iterating over the entire git history using revwalk is expensive and slow for large repositories.

Tasks:

• Add logic to limit the number of commits traversed (e.g., "HEAD~100..HEAD"), or add a date-based filter.
• Make this limit configurable (through a constant, argument, or config file).
• Document the behavior in code comments or README.

Impact:
Prevents performance issues in large repositories and improves CLI tool responsiveness.