1 inch threadless headset with hollow cap for cable routing
You're looking for a Potts Mod, which allows you to route the front brake cable down through the fork's steerer and out to the front brake caliper.

This will allow the front fork/wheel/bars to do a complete rotation without binding on cables.

A Potts Mod does not work for a back brake - for that you require a "detangler" or to fit coaster brakes, aka back-pedal brakes.