v0.6.0 — HexPosition, Cluster.position (field 8), UpdateClusterPosition RPC Adds proto foundation for per-user server-side cluster position persistence (honeycomb-drag-snap). Additive: new HexPosition message, Cluster.position field 8, UpdateClusterPosition RPC on ClusterService. Regenerated Go + TS. Merged via !13 (register-allowing-hagfish).