Cherry-picked from PR #2201 by @Gutslabs.
session_search resolved hits to parent/root sessions but only excluded
the exact current_session_id. If the active session was a child
continuation (compression/delegation), its parent could still appear
as a 'past' conversation result.
Fix: resolve current_session_id to its lineage root before filtering,
so the entire active lineage (parent and children) is excluded.
1870069f80