Implement cleanup function to remove globally installed packages

[konard]

Summary

Implements a comprehensive cleanup function to remove any packages installed by use-m in the global npm context/folder. This addresses issue #24 by providing both programmatic and CLI interfaces for cleaning up globally installed packages.

Changes

✨ New Features

• use.cleanup() function: Programmatically remove all globally installed packages
• CLI cleanup command: Easy command-line interface via use-m cleanup
• Multi-environment support: Works with both Node.js/npm and Bun environments
• Smart detection: Automatically detects environment and skips cleanup for browser/Deno (no global packages)

🔧 Implementation Details

• Scans global npm/bun directories for packages matching use-m alias pattern (package-name-v-version)
• Uses npm uninstall -g for npm environment
• Uses bun remove -g for Bun environment
• Returns detailed results including cleaned packages, errors, and environment info
• Handles edge cases like missing directories and permission errors

📚 Documentation

• Added comprehensive documentation section in README
• Includes both programmatic and CLI usage examples
• Clear explanation of return values and error handling

🧪 Testing

• Added comprehensive test suite for cleanup functionality
• Tests environment detection, error handling, and edge cases
• Tests pass with 15-second timeout to accommodate real package operations

Test Plan

• Test use.cleanup() function returns proper structure
• Test environment detection (npm/bun/browser)
• Test empty directory handling
• Test CLI command functionality
• Test documentation accuracy
• Manual testing with real package installations

Resolves #24

🤖 Generated with Claude Code