Make script/ entrypoints POSIX sh; add bootstrap and setup

script/projectname

@@ -1,9 +1,9 @@
-#!/usr/bin/env bash
+#!/bin/sh
 # script/projectname: output the name of this project. Our own
 # extension to scripts-to-rule-them-all. Other scripts that need the
 # name (e.g. script/docker) call this, so they can stay identical
 # across all repos.
-set -euo pipefail
+set -eu
 
 main() {
     echo "prompts"