Add Vitest

**Goal:** Improve the quality and reliability of our projects by using Vitest + Testing Library as the default testing framework.

**Context:** Currently, our projects lack a consistent and efficient way to test critical features and paths. By using Vitest + Testing Library as the default testing framework, we can provide a unified platform for developers to write tests that ensure code quality and prevent regressions.

**Solution:** Ship our projects with a pre-configured Vitest + Testing Library setup that can be easily customized to fit project-specific needs. While the depth and extension of testing will be defined on a per-project basis, all projects must have their critical features and paths thoroughly tested. This will streamline the testing process, improve code quality, and ultimately result in better-quality products.