Introduce simple position smoothing for normal proxy movement and snap special movements. Adds kProxyPositionLerpAlpha, Lerp/LerpPosition helpers, and ShouldSnapRemoteMovement to lerp proxy position on normal updates while snapping on cell_change, worldspace_change, and teleport. Update MoveProxyToRemotePlayer to use lerp or snap, keep heading snapping (TODO: wrapped angle smoothing), and add throttled/readable logs for smoothing start, first smoothed movement, snaps, and idle-on-cell-mismatch. Minor messaging change on disconnect to leave proxy idle at last position. Update docs (architecture, setup, protocol) and dev log to reflect the new behavior and testing notes; dynamic spawning/multiple proxies remain out of scope.