Enhance Vitest configuration and improve Vue integration

- Added Vue plugin to vitest.config.ts for better component testing.
- Introduced vitest.setup.ts to expose Vue reactivity and lifecycle methods globally, ensuring compatibility with .vue components.
- Updated mock implementations in nuxt-imports.ts to include readonly for improved reactivity handling.
- Refactored useMapBookmarks and useToast composables to utilize readonly from Vue for better state management.

frontend-nuxt/composables/useMapBookmarks.ts

@@ -1,3 +1,5 @@
+import { readonly } from 'vue'
+
 export interface MapBookmark {
   id: string
   name: string