Enhance documentation and automate R package management

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

tools/install_quarto_deps.R

@@ -0,0 +1,59 @@
+#!/usr/bin/env Rscript
+# Script to dynamically detect and install R dependencies from Quarto files
+# Uses the {attachment} package to scan .qmd files for library()/require() calls
+
+args <- commandArgs(trailingOnly = TRUE)
+quarto_dir <- if (length(args) > 0) args[1] else "."
+
+# Target library for installing packages (the mounted volume)
+target_lib <- "/usr/local/lib/R/site-library"
+
+cat("Scanning Quarto files in:", quarto_dir, "\n")
+cat("Target library:", target_lib, "\n")
+
+# Find all .qmd files
+qmd_files <- list.files(
+  path = quarto_dir,
+  pattern = "\\.qmd$",
+  recursive = TRUE,
+  full.names = TRUE
+)
+
+if (length(qmd_files) == 0) {
+  cat("No .qmd files found.\n")
+  quit(status = 0)
+}
+
+cat("Found", length(qmd_files), "Quarto files\n")
+
+# Extract dependencies using attachment
+deps <- attachment::att_from_rmds(qmd_files, inline = TRUE)
+
+if (length(deps) == 0) {
+  cat("No R package dependencies detected.\n")
+  quit(status = 0)
+}
+
+cat("\nDetected R packages:\n")
+cat(paste(" -", deps, collapse = "\n"), "\n\n")
+
+# Filter out base R packages that are always available
+base_pkgs <- rownames(installed.packages(priority = "base"))
+deps <- setdiff(deps, base_pkgs)
+
+# Check which packages are not installed
+installed <- rownames(installed.packages())
+to_install <- setdiff(deps, installed)
+
+if (length(to_install) == 0) {
+  cat("All required packages are already installed.\n")
+} else {
+  cat("Installing missing packages:", paste(to_install, collapse = ", "), "\n\n")
+  install.packages(
+    to_install,
+    lib = target_lib,
+    repos = "https://cloud.r-project.org/",
+    dependencies = TRUE
+  )
+  cat("\nPackage installation complete.\n")
+}