NEAR_DUPLICATE

Dropped because a new entry says the same thing.

Unlike the other three this is not the store running out of room: the entry was still live and still correct. It was replaced because a cache that has answered one question in six phrasings stores six copies of one answer and pays to score all six on every later lookup. Only ever emitted when SemanticCache(deduplicateWrites = …) is set, and only for an entry the guards agreed was interchangeable with the one replacing it.