Render-clock tracking timestamps (menu toggle), physics step cap 6, docs for step 2.7

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/WorldPanel.cs

@@ -79,6 +79,7 @@ public partial class WorldPanel : Node3D
         _menu.ClickVolumeSlider.ValueChanged += v => _click.VolumeDb = Mathf.LinearToDb((float)v / 70f);
         _menu.StrengthChanged += v => PlayerRagdoll.Strength = v;
         _menu.SmoothTurnToggled += on => PlayerRig.SmoothTurn = on;
+        _menu.LowLagTrackingToggled += on => PlayerRig.SteadyTracking = !on;
         _menu.SpectatorToggled += PlayerRig.SetSpectator;
 
         SetPanelActive(false);