Scaffold a custom extension for Adobe GenStudio for Performance Marketing using App Builder — project setup, brand-config bindings, content-fragment integration, the extension manifest, the events the extension subscribes to, and the deploy/test loop. Use whenever the user mentions "GenStudio", "GenStudio extension", "GS4PM", "App Builder", "Adobe Experience Cloud extension", "extend GenStudio", "custom panel in GenStudio", "GenStudio plugin", or wants to integrate a custom workflow into the GenStudio experience. Encodes the early-mover pattern for the GenStudio ecosystem, including the bindings that are documented but rarely shown end-to-end.
