Chore: Upgrade Vitest to v4 (#7797)

## Summary

https://vitest.dev/guide/migration.html#vitest-4

## Changes

- **What**: Update Vitest and some associated dependencies
- **What**: Fix issue with our existing mocks and mock types

## Review Focus

Double check the test updates. I tried to keep the changes minimal.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7797-Chore-Upgrade-Vitest-to-v4-2d96d73d3650810cbe3ac42d7bd6585a)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

src/platform/assets/composables/useMediaAssetGalleryStore.test.ts

@@ -7,10 +7,14 @@ import type { AssetMeta } from '../schemas/mediaAssetSchema'
 import { useMediaAssetGalleryStore } from './useMediaAssetGalleryStore'
 
 vi.mock('@/stores/queueStore', () => ({
-  ResultItemImpl: vi.fn().mockImplementation((data) => ({
-    ...data,
-    url: ''
-  }))
+  ResultItemImpl: vi
+    .fn<typeof ResultItemImpl>()
+    .mockImplementation(function (data) {
+      Object.assign(this, {
+        ...data,
+        url: ''
+      })
+    })
 }))
 
 describe('useMediaAssetGalleryStore', () => {