fix: Simplifies fastwalk detection (#907)

* Uses a circular buffer for steps.
* Limits to 3 steps instead of 4.
* Gives a 5% buffer on the first step.

Projects/UOContent/Network/FastwalkDetection.cs

@@ -0,0 +1,67 @@
+using System.Collections.Generic;
+using Server.Commands.Generic;
+
+namespace Server.Network;
+
+public static class FastwalkDetection
+{
+    private static readonly HashSet<Mobile> _debugFastwalk = new();
+
+    public static void Initialize()
+    {
+        TargetCommands.Register(new DebugFastwalk());
+        EventSink.FastWalk += OnFastwalk;
+    }
+
+    private static void OnFastwalk(FastWalkEventArgs e)
+    {
+        var from = e.NetState.Mobile;
+        if (from == null)
+        {
+            return;
+        }
+
+        if (!_debugFastwalk.Contains(from))
+        {
+            return;
+        }
+
+        from.PublicOverheadMessage(MessageType.Emote, from.EmoteHue, false, "Fastwalk Detected", accessLevel: AccessLevel.GameMaster);
+    }
+
+    public class DebugFastwalk : BaseCommand
+    {
+        public DebugFastwalk()
+        {
+            AccessLevel = AccessLevel.GameMaster;
+            Supports = CommandSupport.AllMobiles;
+            Commands = new[] { "DebugFastwalk" };
+            ObjectTypes = ObjectTypes.Mobiles;
+            ListOptimized = true;
+            Usage = "DebugFastwalk <on|off>";
+            Description = "Enables fastwalk debug messages";
+        }
+
+        public override void ExecuteList(CommandEventArgs e, List<object> list)
+        {
+            var on = e.Arguments.Length == 0 || e.GetBoolean(0);
+
+            foreach (var o in list)
+            {
+                if (o is not Mobile m)
+                {
+                    continue;
+                }
+
+                if (on)
+                {
+                    _debugFastwalk.Add(m);
+                }
+                else
+                {
+                    _debugFastwalk.Remove(m);
+                }
+            }
+        }
+    }
+}