TECH TASK: make dev/prod modes for boost?

STUB

Problem

• boost currently defaults to prod if you supply no -u argument
• this makes it easy to accidentally create channels on prod during local dev work

Potential solution(s)

1. add dev/prod flags (-td/--target-dev and -tp/--target-prod) and require that one of them be set
2. look for a BOOST_MODE env var and require that it be set to either dev or prod