The project currently does not have a centralized API reference
for the core modules inside src/.

I would like to add API documentation to improve developer
experience and make the project easier to understand.

Proposed work:

• Create API_REFERENCE.md
• Document all public functions in src/
• Add parameter descriptions
• Add return values
• Add usage examples

This will help new contributors understand the codebase faster.

I would like to work on this issue.