[Task](greenhouse): remove useAppLoader and auth app to reduce dependencies

[andypf]

Task Description
In the context of All-In-One Deployment with co-located assets, we need to remove the auth app and the useAppLoader hook. This enables us to build and host all applications on the same server as the main app, streamlining the deployment process. Additionally, it allows us to create a Docker image that includes all applications along with the dashboard, simplifying the deployment and scaling of the entire suite.

Sub-tasks

• replace all useAppLoader (from utils package) hooks with code living in the dashboard
• use oauth package directly and extend useCommunication hook to trigger auth events

Related Issues

• [Feature](greenhouse): create Dockerfile to build host app with colocated assets #352

[andypf]

Done!