Agent Skills: prototype

Build a throwaway prototype to flesh out a design before committing to it. Routes between two branches \u2014 a runnable terminal app for state/business-logic questions, or several radically different UI variations toggleable from one route. Use when the user wants to prototype, sanity-check a data model or state machine, mock up a UI, explore design options, or says \"prototype this\", \"let me play with it\", \"try a few designs\".