flint-chart: interactions and updates on a chart

A Flint chart is shared state. A reader's gesture becomes an event, a handler turns the event into an update { id, ops }, updates compose as layers, and the layers render into a state the host and the agent read back. An application and an agent write the same kind of update directly. The full model is in the documentation: https://microsoft.github.io/flint-chart/#/documentation/interaction-introduction

The chart itself (chart_spec, semantic_types) is the flint-chart-author skill. Everything here runs on the Vega-Lite backend; a static render and the other backends leave interaction_spec and updates untouched.

What you produce (and what you do NOT)