dedupKey

The Raft §8 client-serial dedup identity stamped onto this entry by its proposer. Always present — every committed application entry is stamped, including the auto-serial TurnSequencer.propose path. Fold it through a us.tractat.kuilt.raft.ClientSessionTable in the apply loop to preserve exactly-once across forwarding and reconnect: skip the entry when us.tractat.kuilt.raft.ClientSessionTable.shouldApply returns false.