StateSizes

The measured size of the states of each class, for a state cache bounded by bytes: the mean length of their JSON as the EventCodec that measures them writes it (the shared states and snapshots) and reads it (the snapshots loaded), over about its last WINDOW states.

A cached state weighs ENTRY_BYTES (its entry, reference, metadata and the cache's node), TEXT_FACTOR bytes for each character of its class's mean JSON, and what its recent requests' rings take. A class not measured yet weighs CachedState.bytes, the fixed estimate: a domain that has no snapshots and no state readers is weighed as before. Each state is weighed by its class's mean, not its own size, so the cache's total follows the states' while each weighing stays a lookup.