Improve PyHarp documentation #364
Description
Improve PyHarp documentation to match the current Harp API and add clear, minimal examples that show how to handle MIDI, text, and audio inputs. The goal is to provide a simple template that lets developers single-shot implement their own models, even with AI coding assistance. The example models, they can be trivial as long as they clearly show how inputs, controls, and data flow are wired in PyHarp. Strong, up-to-date examples would significantly lower the onboarding barrier and make the framework much easier to extend.