Add support for serving and watching

[matchai]

In local development, I'm usually running headlessly, in watch mode for a quick TDD feedback loop. But when I get an unexpected failure, I only have the results shown in console to work with.

Ideally, I think we should follow the conventions of @vitest/ui:

When running vitest --ui, it runs in watch mode and runs the server. You can navigate to its URL for a more detailed results view, but can otherwise use it for TDD work, watching the console.

Similarly I think we should have watch expose a server.

[mattpocock]

I'm a little confused by what you mean. Evalite already exposes a UI at localhost:3006

[matchai]

Total slip-up on my end. Not sure I how I missed that watch also exposes the server 🫠
Thank you for the quick response!