Register Architect commands in service provider

[ibourgeois]

Context

As a Nebula user, I need the Architect commands to be automatically registered when the package is installed.

Acceptance Criteria

• Create ArchitectServiceProvider class
• Register all Architect commands in the provider
• Publish Architect configuration if needed
• Ensure service provider is auto-discovered via composer.json
• Test that commands are available after package installation
• Document how to extend with custom commands