Add missing files for Vue frontend

Don't add files to the staging area while IntelliJ is indexing, I guess.

vue/babel.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  presets: [
+    '@vue/app'
+  ]
+};

vue/src/main.js

@@ -0,0 +1,10 @@
+import Vue from 'vue'
+import App from './App.vue'
+import router from './router'
+
+Vue.config.productionTip = false;
+
+new Vue({
+  router,
+  render: h => h(App)
+}).$mount('#app');