v0.3.8

Added

• Configurable cluster-control payload signing via extensions.node.cluster_control.auth.mode (auto, required, disabled), with timestamp freshness and nonce format validation when signing is active.

Changed

• ClusterControl queues now read durability and retention settings from extensions.node.cluster_control.queue; defaults remain durable and non-auto-delete so per-node commands survive node restarts.
• Beat no longer runs immediately at actor construction, avoiding startup reconciliation before extension boot completes.
• update_gem now installs through Legion::Extensions::GemSource and calls extension-scoped reload instead of full daemon reload.