Improve package.yml parse error

Refs pkgxdev#238

prevent fork bombs

[ci] separate out .md lint (pkgxdev#218)

fix typo

gardening

move interpreter detection to package.yml (pkgxdev#150)

Don’t double up args (pkgxdev#200)

Fixes pkgxdev/demos#7

read the shebang and magically hydrate deps

remove spurious `console.log` 🤦‍♂️