V63 deduplicates any phantom (group_id, permission) rows accumulated since the initial schema. V64 sets NOT NULL on permission and adds pk_group_permissions. V65 renames uq_tbmp_block_person to pk_tbmp for naming-convention consistency. Integration tests confirm each constraint via pg_catalog.pg_constraint. Closes #469 (partial). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>