Update documentation to reflect that all tools are provided via a builder Docker image
- Simplify prerequisites section in Readme.md
- Add detailed explanation of the builder image and its role
- Document R package caching mechanism for faster builds
- Update start-jupyterhub.sh to build and use the builder image
- Add Dockerfile.builder to provide the build environment
- Implement automatic R dependency detection and installation
- Update Slides.qmd to use gt package for better table formatting
