Fix toggleTheme method to update theme and store

it in local storage

src/plugins/vuetify.js

@@ -11,9 +11,12 @@ import 'vuetify/styles'
 // Composables
 import { createVuetify } from 'vuetify'
 
+const defaultTheme = localStorage.getItem('theme') || 'light'
+
 // https://vuetifyjs.com/en/introduction/why-vuetify/#feature-guides
 export default createVuetify({
   theme: {
+    defaultTheme,
     themes: {
       light: {
         colors: {