add shellspec golden harness for the legacy make engine

- spec/golden/cases.txt: 69 black-box cases (CLI wrapper mode and make
  include mode) run in a hermetic sandbox with a mocked docker
- spec/golden/expected/*.txt recorded from this engine (baseline)
- make test / test-golden / golden-record / lint dev targets

spec/support/bin/docker-compose

@@ -0,0 +1,4 @@
+#!/bin/sh
+[ -n "${MYOS_DOCKER_LOG:-}" ] && printf 'docker-compose %s\n' "$*" >> "$MYOS_DOCKER_LOG"
+case "$1" in version) echo "${MOCK_COMPOSE_VERSION:-2.29.0}" ;; config) echo "# mock compose config" ;; *) : ;; esac
+exit 0