The repo for the Bower package can be found here. There is also a repo with examples on how to do local builds using Dojo and RequireJS.
Easy Bower Install
bower install --save arcgis-jsp-api
If you’ve been using the esrislurp tool to download the ArcGIS JS API from the CDN to your machine, then the Bower package is definitely something you would want to use.
The Bower package has not been run through any build system, just minified. This means you can customize the build as much as you would like. You can read more about the Dojo build process here.
For details, watch this video that covers all the steps using both Dojo and RequireJS.