feat(\db-tool\): introduce unified db-tool package with postgres harness and tests (T0-T8)

package/db-tool/postgres-cleanup.sh

@@ -0,0 +1,14 @@
+#!/bin/dash
+
+postgres_cleanup_main() {
+  if [ -z "${PG_WORKING_DIR:-}" ] && [ -z "${LOCAL_DIR:-}" ]; then return 0; fi
+  : "${PG_WORKING_DIR:=$LOCAL_DIR/focus/postgresql}"
+  if [ -f "${PG_WORKING_DIR}/data/postmaster.pid" ]; then
+    pg_ctl -D "${PG_WORKING_DIR}/data" -m fast -w stop || :
+  fi
+  return 0
+}
+
+if [ "$(basename "$0")" = 'postgres-cleanup' ]; then
+  postgres_cleanup_main "$@"
+fi