How to use CWHYEVICT: ask why an entry would be dropped

Crowkis evicts by composite retention, not plain LRU. CWHYEVICT shows the component scores for a given entry so you can see why it's safe or at risk.

> CWHYEVICT "how do refunds work?" TENANT acme
1) "retention=0.81  pinned=false"
2) "recency=0.6 frequency=0.9 isolation=0.4 cost=0.95"

A high cost score is why an expensive reasoning answer outranks a cheap, recently-hit triviality under memory pressure.