Integrate Vuetify layout and routing

Add a Vuetify-powered application shell (Layout.vue) replacing the previous App.vue, including app bar, navigation drawer, theme toggle, footer and localStorage persistence for theme/drawer. Introduce a routesLayout plugin with a Visibility enum and centralized LayoutRoute definitions; add route components (Home, Impressum, Login, 404NotFound) and update the router to build routes from the new layout definitions. Register Vuetify in main.ts and add dependencies (vuetify, @fontsource/roboto, @mdi/font) in package.json; update tsconfig.app.json to include .ts files. Package-lock.json updated accordingly.

GUI/src/main.ts

@@ -1,12 +1,14 @@
 import { createApp } from 'vue'
 import { createPinia } from 'pinia'
 
-import App from './App.vue'
+import App from './Layout.vue'
 import router from './router'
+import vuetify from './plugins/vuetify'
 
 const app = createApp(App)
 
 app.use(createPinia())
 app.use(router)
+app.use(vuetify)
 
 app.mount('#app')