I ran npm install
to get the dependencies in the package.json so I could run the script locally before uploading (a very important feature IMHO). However, this added argo, express, etc. to the zip which put it over the size limit.
Removing the node_modules directory does fix the 413 error. I will add something to my build toolchain that removes the apigee provided dependencies from the node_modules directory before trying to upload.