Webpack: how to move Aurelia code to vendor bundle from app bundle


I’ve cloned the skeleton-navigation repo, and tried building both esnext- and typescript-webpack apps.
In both cases the app.js is much bigger than vendor.js (around 3 Mb of app.js comparing to 1.5 of vendor.js) and it seems it contains all the aurelia-framework code.
I guess this is due to ‘aurelia-bootstrapper’ being an entry point of app bundle?
How do I move the framework to vendor bundle, so that the app bundle contains my actual (tiny) application code ?