Release 1.5.0 Ergonomic and observability improvements over 1.4.0: - retry_jitter parameter to spread retries and avoid thundering-herd against a shared downstream. - observer lifecycle hook emitting (event, payload) at started / iteration_end / iteration_error / retry_scheduled / paused / resumed / stop_requested / stopped / cancel_requested / cancelled / failed. - asyncio.Event-based pause gate: stop and cancel during a paused loop now wake immediately instead of waiting up to time_pause seconds. Suite: 43 -> 50, coverage 94% -> 95%.