Web-based playground editor
It would be neat to have an easily accessible editor for live coding. Something like the [TypeScript Playground](https://www.typescriptlang.org/play) with the code on the left and the game on the right, with the ability to inspect the WAT and download the `cart.wasm`.

AssemblyScript seems like it would be a perfect fit for this! @MaxGraey :eyes: Maybe the existing AS editor could be repurposed?