Latency floor (Sara): a merge-blocking regression check, not a benchmark. Seeds 200 blocks each with one mention of the same person, fires the rename, and asserts the listener completes the entire find/mutate/saveAllAndFlush cycle in less than two seconds against the Testcontainers Postgres. Confirms the partial reload (one Auguste → Augusta) actually persisted so the timing isn't measuring an empty path. Refs #362 Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>