Add test coverage for NAPI and Python bindings

[danbugs]

Currently the repository has comprehensive Rust integration tests but lacks dedicated test coverage for language-specific bindings.

Scope:

• Add tests for NAPI (Node.js) bindings
• Add tests for Python (PyO3) bindings

Test areas:

• Verify bindings correctly expose underlying functionality
• Error handling (invalid files, runtime errors, etc.)
• API contracts (return types, method signatures)
• Async/await behavior
• Resource cleanup

Suggested structure:

• tests/napi/ - Node.js test suite (using Jest or similar)
• tests/python/ - Python test suite (using pytest)

Related to PR #20 review feedback from @copilot-pull-request-reviewer