Window-level event dispatched by AbstractShowcase once start() has finished setting up
the scene (including awaited asset loads) and the render loop has produced a stable frame. Lets
external tooling (preview, visual QA, e2e tests) hook into readiness instead of racing a fixed
delay. The event's detail carries the resolved renderer type, so consumers can also verify
which backend actually came up.
Window-level event dispatched by AbstractShowcase once
start()has finished setting up the scene (including awaited asset loads) and the render loop has produced a stable frame. Lets external tooling (preview, visual QA, e2e tests) hook into readiness instead of racing a fixed delay. The event'sdetailcarries the resolved renderer type, so consumers can also verify which backend actually came up.