ANU-7: Migrate Supabase Postgres data and verify local cutover

This directory records the repository-owned implementation and verification for ANU-7, the data-migration child of Product Main change 2026-07-20-switch-to-local-postgres.

• Implementation plan
• Implementation log
• Completion report

The migration keeps the Supabase source read-only, writes dumps and redacted evidence only to ignored local storage, restores into the accepted local Postgres/pgvector stack, and retains a tested connection rollback path.