fix: correct package.json exports configuration and add comprehensive tests

[pravaahm-ai]

Description

Fixed package.json exports configuration to properly support all three module exports (main decision tree, xgboost, and random-forest). Added comprehensive test coverage to validate package.json configuration and prevent future regressions.

Changes Made:

• Corrected exports configuration in package.json to include all required module exports
• Added 22 comprehensive test cases in tst/package-configuration.ts covering:
  • Export configuration validation
  • File system verification of exported files
  • Package metadata validation
  • Dependencies and scripts verification

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Test addition/improvement

Testing

• All existing tests pass
• New tests added for new functionality (22 tests in package-configuration.ts)
• Manual testing completed (verified exports work correctly)
• Performance impact assessed (if applicable - basic tests only)
• Edge cases tested (file existence, export consistency)

Checklist

• Code follows existing style guidelines
• Self-review completed
• Documentation updated (if needed)
• No breaking changes (or clearly documented if intentional)
• TypeScript types are properly defined
• Error handling is appropriate
• Performance considerations addressed