Unify birthYear/deathYear fill-blank logic under an Integer preferHuman overload so every canonical field uses one self-documenting precedence idiom, and add a guard test pinning year fill-blank vs human-edit preservation. Add a comment in PersonTreeImporter.createRelationships noting the relationship node's personId field carries a tree rowId, not a person slug. Refs #669 Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>