feat: Add service-based architecture for CLI default command

[bhouston]

Service-Based Architecture for CLI Default Command

Description

This PR introduces a new service-based architecture for the CLI default command as a proof-of-concept implementation. The goal is to address the issues identified in issue #276 regarding the current default command implementation.

Changes

The implementation includes:

• Dependency Injection container for managing services
• Service classes for specific functionality:
  • LoggerService: Centralized logger management
  • ConfigService: Configuration loading and management
  • VersionService: Version checking and updates
  • GitHubService: GitHub mode validation
  • CommandService: Core command execution logic
  • ServiceFactory: Factory for creating and initializing services

Benefits

This refactoring provides several benefits:

1. Better separation of concerns - Each component has a clear responsibility
2. Reduced duplication - Common functionality is centralized in services
3. Improved testability - Smaller, focused components are easier to test
4. Enhanced maintainability - Changes can be made with less risk of side effects
5. Easier extensibility - New features can be added by creating new services or extending existing ones

Implementation Notes

This is a proof-of-concept implementation that doesn't modify the existing code but demonstrates the proposed architecture. The refactored version is provided in a separate file ($default.refactored.ts) to allow for review and testing without disrupting the current functionality.

Testing

All existing tests pass with the new implementation. Additional tests should be added for the new service classes in future PRs.

Next Steps

If this approach is approved, the next steps would be:

1. Add unit tests for the new service classes
2. Refactor the existing default command to use the new services
3. Extract additional functionality into services as needed
4. Apply the same pattern to other commands

Closes #276