ctxerrors v0.5.0 — add the commerr sentinel subpackage commerr holds the shared common sentinel errors (ErrNotFound, ErrAlreadyExists, ErrFetchFailed, ErrTimeout, and the rest) that SetErrorMap translates into -- previously only in common-go/errors. Plain errors.New values, matched with errors.Is through any Wrap depth. A subpackage, so wrapping-only consumers do not compile it. common-go/errors becomes a deprecated re-export of these.