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/lib/__tests__/Character.test.ts

@@ -4,29 +4,36 @@ import type L from 'leaflet'
 import type { Map, LayerGroup } from 'leaflet'
 import { createCharacter, type CharacterData, type CharacterMapViewRef } from '../Character'
 
-vi.mock('leaflet', () => {
+const { leafletMock } = vi.hoisted(() => {
   const markerMock = {
     on: vi.fn().mockReturnThis(),
     addTo: vi.fn().mockReturnThis(),
     setLatLng: vi.fn().mockReturnThis(),
     setIcon: vi.fn().mockReturnThis(),
   }
-  return {
-    default: {
-      marker: vi.fn(() => markerMock),
-      Icon: vi.fn().mockImplementation(() => ({})),
-    },
+  const Icon = vi.fn().mockImplementation(function (this: unknown) {
+    return {}
+  })
+  const L = {
     marker: vi.fn(() => markerMock),
-    Icon: vi.fn().mockImplementation(() => ({})),
+    Icon,
   }
+  return { leafletMock: L }
 })
 
+vi.mock('leaflet', () => ({
+  __esModule: true,
+  default: leafletMock,
+  marker: leafletMock.marker,
+  Icon: leafletMock.Icon,
+}))
+
 vi.mock('~/lib/LeafletCustomTypes', () => ({
   HnHMaxZoom: 6,
 }))
 
 function getL(): L {
-  return require('leaflet').default
+  return leafletMock as unknown as L
 }
 
 function makeCharData(overrides: Partial<CharacterData> = {}): CharacterData {