These were already in .gitignore but had been committed before the
.gitignore rule was added, so git was still tracking changes to
them — every rebuild dirtied the working tree with compiled .beam
artifacts and the occasional crash dump landed in commits.
`git rm -r --cached` removes them from the index without deleting
from disk. Future builds won't show in `git status` anymore.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
