evmts/xvi: XVI - Ethereum execution client (vibe-coded!)

XVI is an experiment in building an entire Ethereum execution client with AI agents writing every line of source code, orchestrated by Smithers, with humans supplying only architecture, specs and test targets. The project has two parallel client implementations, a Zig client at about 70% feature-complete and an Effect-TS client at about 65%, both mirroring Nethermind's architecture across 11 subsystems. The EVM engine Guillotine reportedly passes 100% of ethereum/tests from Frontier through Prague. Key gaps include the consensus engine, persistent RocksDB storage, full networking and the Engine API, and testing and polish phases have not started for either client.