Record pruning

After each successful consume, timestamps older than every active time-based rule needs are removed. The remaining list is then capped to the newest maxHits entries (default 100); the lifetime counter is separate.

Choose maxHits at least as large as the greatest number of hits that any active sliding/calendar rule may need to count. Too small a value can undercount a high quota and allow early. Changing rule sets later cannot recover already pruned timestamps. Cooldown remains correct because the newest hit is retained.