Set up a multi-repo workspace

This guide puts several repositories into one workspace. A work item that changes two repositories then becomes one case, and the steering report groups them.

1. Run casebox init --workspace checkout in each repository, with the same workspace name. Each repository joins the workspace.

2. List every repository in each casebox.yml of the workspace:

   workspace: checkout
   repos:
     - github.com/acme/checkout-api
     - github.com/acme/checkout-web

3. Write one environment recipe for all of them. When the repositories build from source together, name the files that link them under links, such as go.work, project references or an npm workspace file.

Cases come in three scopes:

Scope	What the agent gets
Single	One sealed repository.
Split	The case’s repository sealed; the other repositories of the work item at their merged state.
Multi	Every repository sealed side by side under one folder, each at its own base commit. Casebox needs links for this.

Repositories that depend on each other only through published packages are not supported in 0.1.0, because such a case needs the historical package versions.