Sandbox cleanup of planted bare Git repositories was reworked

The sandbox is a restricted space where Claude Code runs commands with limited access to your system. A bare repository is a Git repository without a working copy of files, made of entries such as HEAD, objects and refs. Claude Code's cleanup that removes such files when they have been planted has changed. It removes those files, then falls back to removing empty folders, or the whole directory if a HEAD file is still there. It logs each file it removes.