SaltedCoinsCacheHasher

Description

Retained entries identify real transaction outputs, so their keys contain computed txids. Missing-input lookups may contain arbitrary claimed prevouts, but FetchCoin() immediately erases their temporary entries when the backend lookup fails, so non-hash keys cannot accumulate.

The assumeutxo loader assumes snapshot txids are valid while loading and verifies the complete snapshot's content hash before activation.

Hash values are process-local and must not be persisted, serialized, or compared across processes.

Having the hash noexcept lets libstdc++ recalculate it during rehash instead of storing it in each node.