Incoprorate pntr_app_web

[konsumer]

I think it would be cool to put pntr_app_web in this repo, and get a nice demo building in CI. This would mean others can link directly to the js/wasm for it, and use it easily in codepens, but also it would mean we can make a nice intro page with pntr_app demos running inside it, with source-code, to show off how cool it is.