15faada234
- Replace monolithic build flow with three operating modes: pull (default), local-build, publish - Add version.txt for image tagging and multi-platform builds via buildx (--publish) - Switch builder to tarball-based Quarto install for better cross-platform reliability - Update docker-compose.yml and jupyterhub_config.py to use environment variables for image names, defaulting to registry images - Refactor start-jupyterhub.sh: modular functions for image management, clearer flag handling and error messages - Simplify Readme.md with structured tables instead of dense paragraphs, clarify data persistence and R package workflow