Nuxt Test Utils v4: Vitest v4 Requirement, Mocking Overhaul and Stricter Environment Setup

Nuxt Test Utils has released version 4.0.0, which primarily integrates Vitest v4. This update changes the test environment setup to beforeAll, resolving issues with module-level mocks. It also improves mockNuxtImport for cleaner partial mocking and enhances state management for registered endpoints. The library remains vital for testing in the Nuxt framework, bridging unit and end-to-end testing.