Authoring motion diagrams

Every marketplace entry has one authored scene at scripts/animations/scenes/<plugin>.svg, shown on that plugin's detail page. docs/plugins/<plugin>/anim.mp4 and anim-poster.png are derived from it. Never patch the video — change the scene and re-render.

A scene must say what the plugin does: what moves, in what order, and what is different at the end. A scene where things merely move is decoration.

Flow