Install only missing packages across all common-utils package sets

[Copilot]

✨ Enhancement

What does this improve?
The previous change only applied “install if missing” behavior to bubblewrap and socat. This expands that behavior to the full distro-specific package sets in common-utils, so prebuilt images avoid redundant installs while still converging to the expected package baseline.

Why is this valuable?
It preserves idempotent behavior for images that already contain part (or most) of the toolchain, reduces unnecessary package operations, and keeps feature behavior consistent across Debian/Ubuntu, RHEL-family, and Alpine.

Implementation approach:

• Debian/Ubuntu path
  • Build the full intended package list (including conditional entries).
  • Compute missing_package_list via dpkg-query.
  • Install only missing packages with apt-get.
• RHEL-family path
  • Build the full intended package list (including conditional entries).
  • Compute missing_package_list via rpm -q.
  • Install only missing packages via the detected package manager.
• Alpine path
  • Build the full intended package list (including conditional entries).
  • Compute missing_package_list via apk info -e.
  • Install only missing packages with apk add.
• Safety/robustness
  • Parse package lists into arrays before iteration to avoid shell glob expansion issues (notably for bracketed package patterns).

read -r -a packages <<< "${package_list}"
for package in "${packages[@]}"; do
    if ! dpkg-query -W -f='${db:Status-Abbrev}' "${package}" 2>/dev/null | grep -q '^ii'; then
        missing_package_list="${missing_package_list} ${package}"
    fi
done

[chrmarti]

A few review notes on the per-package install change. The core direction looks great — these are mostly small follow-ups.

Dead variable (issue 2): With the per-package check now inlined, PACKAGES_ALREADY_INSTALLED no longer gates anything inside install_debian_packages / install_redhat_packages / install_alpine_packages (it's still loaded from the marker file in the main section and set at the end of all three functions, but the guards that used to read it are gone — see lines 166, 285, 367 in src/common-utils/main.sh). The variable is effectively dead within these functions. Worth a follow-up cleanup, either here or in a separate PR, to avoid confusion for future readers.

README/NOTES (issue 5): bubblewrap and socat aren't mentioned in src/common-utils/README.md or src/common-utils/NOTES.md. Since the feature advertises a curated set of common command-line utilities, it's probably worth listing them (and noting the bubblewrap dependency, since it's a less obvious addition than socat).

[chrmarti]

Thanks!