Third canonical loader. Reads canonical-persons-tree.json, upserts tree
persons via PersonService keyed on the shared personId slug (#670 now
emits it into the tree, so the tree reconciles with the register rather
than duplicating it). Relationships are resolved from local rowIds to the
upserted person UUIDs and created via RelationshipService (never the
repository). A duplicate/circular relationship on re-import is swallowed
for idempotency; unresolved rowIds are skipped with a warning.
Refs #669
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
cbf1984430