feat: add Python/pip support to CLI scanner

[yuchengpersonal]

Summary

This PR adds support for scanning Python dependencies, addressing issue #2.

Changes

• Added parseRequirementsTxt() function: Parses requirements.txt files and extracts package names (handles various version specifiers like ==, >=, etc.)
• Added parsePyprojectToml() function: Parses pyproject.toml files and extracts dependencies from the [project] section
• Added readRequirementsTxt() and readPyprojectToml() functions: Handle file reading and validation for Python project files
• Updated readPackageJson() function: Now detects Python project files first, falling back to package.json if no Python files are found
• Updated error messages: Now mention all supported file types (package.json, requirements.txt, pyproject.toml)

Usage

Users can now run the scanner in Python projects:

# In a directory with requirements.txt or pyproject.toml
npx oss-health-scan

# Or specify a directory
npx oss-health-scan path/to/python-project

Testing

Tested with sample requirements.txt:

• Correctly parses package names with various version specifiers
• Ignores comments and empty lines
• Handles -r and other pip options gracefully

Related Issue

Fixes #2