Artifact publish now refuses to overwrite a version it knows is behind

What

• The artifact-publish logic gained a "stale version guard" that denies publishing (with reasons like stale_version_guard or stale_version_guard_before_card) when the session hasn't read or published the artifact recently, along with new consent wording for publishing artifacts outside your organization and a check that affects when a publish can be auto-approved.
• A related guard now runs specifically when the client's tracked base version is defined but known to be stale ("behind") relative to the live version: it re-reads the artifact tagged as "known_behind", and if that read still resolves to real text, the publish is refused with reason code known_behind instead of silently overwriting the newer live version.

Why

This prevents a session from accidentally overwriting someone else's newer changes to an artifact when its own local copy of the version is out of date.