chore: 🤖 Add postinstall step for electron app

ui/connect-client/package.json

@@ -13,7 +13,8 @@
     "lint:hbs": "ember-template-lint .",
     "lint:js": "eslint .",
     "start": "ember serve",
-    "test": "ember test"
+    "test": "ember test",
+    "postinstall": "cd electron-app && yarn install"
   },
   "devDependencies": {
     "@ember/optional-features": "^1.3.0",