ContextResolution

Response of GET /api/contexts/resolve — a context ref resolved to its id, for the caller.

Deliberately just the id: a caller that holds a ref (@me/<slug>, @<handle>/<slug>,
+<team>/<slug>, or a bare UUID) and needs to address one of the id-keyed
/api/contexts/{id}/… routes resolves once here, then calls the route it wanted. Anything
more about the context is GET /api/contexts/{id}'s to answer.