0325 — deliveries went per-topic, and the six remaining shared tables were singularized, before the audit table shipped

Context. The new attempt audit table was about to be created. Making it a shared table would have repeated the shared-table blast-radius mistake already corrected once for messages, and deliveries itself was still shared.

Decision. deliveries became per-topic (delivery_<topic_id>) first, so delivery_log_<topic_id> could be per-topic from the start. Alongside, the six remaining shared tables were renamed to singular: cursors to cursor, leases to lease, bindings to binding, topics to topic, latest_keys to latest_key, idempotency_keys to idempotency_key.

Consequences. One round of schema churn accepted so the audit table never inherits shared-table blast radius; per-topic table families and singular shared-table names become the standing conventions.