Proposal #93: Upgrade devshard v4 runtime to v4.0.1

Replace the existing devshard v4 runtime with v4.0.1. This performance and resource-management patch does not change protocol, inference, validation, or economic behavior. It removes per-block chain queries by switching epoch tracking to event-driven updates and aligns in-memory host-session and validation-worker cleanup with epoch pruning. versiond will automatically download and verify the replacement binary; no mainnet restart or manual host action is required.