renderer: set default i18n language from current system locale

src/renderer/assets/js/utils/index.js

@@ -0,0 +1,5 @@
+export default class Utils {
+  static getCurrentLocale () {
+    return navigator?.language?.split('-')[0] || 'en'
+  }
+}

src/renderer/plugins/i18n.js

@@ -1,13 +1,16 @@
 import { createI18n } from 'vue-i18n'
 import en from '../../locales/en.json'
+import ko from '../../locales/ko.json'
+import Utils from '../assets/js/utils'
 
 // eslint-disable-next-line new-cap
 export default createI18n({
   legacy: false,
-  locale: 'en',
+  locale: Utils.getCurrentLocale(),
   fallbackLocale: 'en',
   globalInjection: true,
   messages: {
-    en
+    en,
+    ko
   }
 })