convert of login items keeps original env names in fields; env now also
exposes the login triple so sourced consumers can map to legacy names.
Ticket: https://projects.knownelement.com/issues/832
Founder follow-up: lifted items restructured to proper login items
(first-class username/password/URIs, remainder as named custom fields).
Classified from the env-key semantics; zero data loss.
Ticket: https://projects.knownelement.com/issues/829