How to use Bolt.new: build an app from a prompt

Bolt.new turns a prompt into a running full-stack app in your browser, with no local setup, because StackBlitz runs the whole dev environment in a browser tab. The thing to understand before you start is the meter: Bolt bills by tokens, with a real free daily allotment. Here is the whole thing, first build to owning the code, and how to make those tokens last.