Nethermind v1.39.0 Hardens Sync, Adds eth/71 and EIP-7928

Nethermind v1.39.0 ships 337 changes. It hardens sync restart safety, overhauls Flat DB durability, and adds eth/71. Eight new JSON-RPC methods and EIP-7928 BAL devnet-7 support are included. OP Karst activates July 8, 2026, 16:00:01 UTC. Operators must upgrade to 1.38.1 or later.