v0.3.0

dbfwd.ListURL(backend, scope, where...) builds the URL of a listing from a scope that a person typed and the fields that edit it, such as the namespace and the context. dbfwd list and the \k command of usql both call it, so the two read a scope in the same way. The backend owns the rules, so the root package names no Kubernetes term. For k8s, the k:// is optional, cnpg://* is k+cnpg://*, and a field that disagrees with the scope is an error that wraps ErrBadURL.

Lister gains the method ListURL, so a backend outside dbfwd that implements Lister must add it.

D18, the listing of the databases of a cluster, is now Decided.