Make sure embedded node modules are installed on install.

Author: davidmurdoch

package.json

@@ -36,7 +36,8 @@
     "test-jest": "jest __tests__/.*.test.js",
     "test-mocha": "cross-env GANACHE_DEV_MODE=true ELECTRON_APP_PATH=./ mocha --require @babel/register --check-leaks 'test/mocha/**/*.test.js'",
     "storybook": "start-storybook -p 6006",
-    "build-storybook": "build-storybook"
+    "build-storybook": "build-storybook",
+    "postinstall": "cd static/node && npm ci --only=prod"
   },
   "dependencies": {
     "@exponent/electron-cookies": "^2.0.0",