PR #1422 deleted the only file in .devcontainer/context/
(reinstall-cmake.sh) as unused, which silently removed the directory
itself since git doesn't track empty ones. Every devcontainer.json
under .devcontainer/ (root and all compiler variants) references this
path as its Docker build context, so opening the project in a dev
container now fails immediately with:
ERROR: failed to build: unable to prepare context: path
".../.devcontainer/context" not found
Add a .gitkeep placeholder to keep the directory present in git so
the build context resolves again.
Co-authored-by: John Wellbelove <jwellbelove@users.noreply.github.com>