fix: versions output — compact local row using \$SHELL, add macos entry

feat: add --os flag, local target, shell/macos, rename to shell-version

test: add echo -e and sed -i portability fixtures

chore(docker): add make to all shell images

chore(docker): add curl and shellcast-version scripts to all shell images

Small amends

Small amends

Small amends

Small amends

Small amends

Initial commit