feat: Users API, ownership transfer and removal of the legacy role string

internal/domain/role/roleDomain.go

@@ -27,6 +27,7 @@ var (
 	ErrNotBuiltIn         = errors.New("role is not built in")
 	ErrInvalidReassign    = errors.New("invalid reassign target")
 	ErrEscalation         = errors.New("grants more than the caller holds")
+	ErrUnknownRole        = errors.New("unknown role")
 )
 
 type Scope string