NON_USER_RELATIONSHIPS

Everything ALL extracts, PLUS relationships a non-user entity explicitly states about itself or another non-user entity, using whatever relationship types the extraction schema already declares. Opt-in; the default stays ALL. Lets a consumer mine e.g. a correspondent's own employer from their signature — facts the user-centric default guidance otherwise suppresses because the user is not a participant.

This stays a value of the existing perspective enum deliberately: it composes with neither USER nor AGENT (a single call has one perspective). The day a consumer needs "non-user relationships" AND a user/agent lens at the same time, that is the signal to promote it to its own orthogonal setting rather than adding more enum values here.