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/tsconfig.app.json

@@ -1,6 +1,6 @@
 {
   "extends": "@vue/tsconfig/tsconfig.dom.json",
-  "include": ["env.d.ts", "src/**/*", "src/**/*.vue"],
+  "include": ["env.d.ts", "src/**/*.vue", "src/**/*.ts"],
   "exclude": ["src/**/__tests__/*"],
   "compilerOptions": {
     // Extra safety for array and object lookups, but may have false positives.