Add a smoke test

[SeanKilleen]

As part of #251, I realized that our tests didn't catch the issue because we don't have a smoke test in place that actually attempts to load the whole JS package (which would have caught the webpack issue with loading JS files).

We have an HTML page that we use for integration tests. I wonder how difficult it would be to load that in a browser window (real via cypress or via JSDom if possible), run the summarizer JS loader code, and then assert that the summarizer window is present?