Modernize package.json and update CI infrastructure

[knowledgecode]

Summary

• Update package.json to follow modern best practices and npm recommendations
• Migrate from CircleCI to GitHub Actions for CI/CD
• Add new development scripts and optimize package configuration

Changes Made

Package Configuration

• Modernized package.json structure: Reordered fields according to npm best practices
• Added ES modules support: Set type: "module" and added modern exports field
• Enhanced tree shaking: Added sideEffects: false for better bundling optimization
• New development scripts: Added build:watch and test:watch for improved development experience
• Updated dependencies: Upgraded all dev dependencies to latest versions

CI/CD Migration

• Replaced CircleCI with GitHub Actions: More integrated CI solution
• Updated badges in README: GitHub Actions and npm version badges
• Removed legacy files: Cleaned up .circleci/config.yml and .npmignore

Development Experience

• Watch mode support: New scripts for automated rebuilding and testing
• ES modules compatibility: Updated test imports for module system
• Cleaner gitignore: Updated exclusion patterns

Test Plan

• All existing tests pass (99 test cases)
• Build process works correctly with new configuration
• New watch scripts function properly
• GitHub Actions CI pipeline validates changes