Pull custom fonts from npm package / node_modules

The custom fonts should be pulled from an npm package (i.e., the node_modules folder) when the site is built instead of being hosted in the source tree for this site. If the fonts are going to be subsetted as an optimization, that process should be done as part of the build. The current situation of storing subsetted fonts directly in the source tree for this site is not maintainable and makes the built hard to understand.

Furthermore, no font files should be loaded from Google Fonts. That violates our privacy requirements (since Google Fonts adds unwanted tracking). It's unnecessary anyway since the site's build already provides an opportunity to retrieve and publish these files as part of the site.