Force rerun of Keybase Installer on macOS

I recently installed Keybase from the DMB on a new macOS computer (albeit with a home directory restored from an older computer). The installation of the GUI app seems to have worked, but the install script to install the `keybase` command-line tool, KBFS, etc. did not, and I can't get it to run again by reinstalling the DMG. Is there a way to re-run this install script manually? I tried `Applications/Keybase.app/Contents/SharedSupport/bin/keybase install`, but that gives Permission Denied errors when trying to create symlinks in /usr/local/bin (understandable).

Start with Applications/Keybase.app/Contents/SharedSupport/bin/keybase and reproduce the install command on macOS, noting the Permission Denied errors when creating symlinks in /usr/local/bin. Trace how the DMG installation invokes the installer and identify a supported way to rerun it. Done means the command-line tool and KBFS installation can be rerun successfully after the GUI app is already installed.

Written by the indexing model from the issue text.