feat: T2A ping-pong mechanic and consider sins behaviour (#2356)

## Summary

- Adds `Mobile.Murderer` virtual property and consolidates kill-threshold checks across the codebase
- Tracks ping-pong count: how many times a player crosses the 5-kill murderer threshold (T2A/UOR/UOTD only, disabled on LBR+)
- Adds `[CommandProperty]` to view a player's ping-pong count via the admin panel
- After enough ping-pongs, player is permanently flagged as a murderer regardless of kill count
- Accounts for perma-red players with low kills in murderer status transition notifications
- Implements era-appropriate "I must consider my sins" speech responses:
  - **T2A**: contextual cliloc flavor text (502122–502126)
  - **UOR–AOS**: raw short/long-term murder counts + ping-pong count if applicable
  - **SE+**: localized stats message (1114370)
- Refactors kill-report logic out of `Keywords.cs` into `PlayerMurderSystem.ReportKillsToSelf`

## Testing

- [x] Thoroughly tested and self reviewed
- [x] Test T2A "I must consider my sins" behaviour over all scenarios.
- [x] Test UOR "I must consider my sins" behaviour over all scenarios.
- [x] Test that LBR does not have ping pongs enabled (I must consider my sins)
- [x] Test serialization cross over from v0 -> v1 increments 1 ping pong if player is already red.

## Notes
* Manually setting kills to 5 does not trigger a ping pong, it must go through the actual murder system. This includes if the kills were manually set to 5 and then migrated (as manually setting kills to 5 never adds the player into the murder system - it only happens via ReportMurderer). This is arguably a bug in the existing system, but one that currently only ever happens via staff interaction.
* Thieves guild SuspendOnMurder specifically checks for kills > 0. This means a person with 0 shorts but 5 ping pongs (flagged as murderer) can steal. This may be accurate, as according to a forum post this is how it works on UOSA which is the T2A gold standard.
* This doesn't implement Pre-T2A behaviour which should be that "I must consider my sins" does nothing at all. The reason I didn't implement it for Pre-T2A is then it 100% have to sit behind a feature flag. I don't mind adding it as a feature flag, just let me know.

Projects/UOContent/Engines/Player Murder System/PlayerMurderSystem.cs

@@ -29,6 +29,8 @@ public class PlayerMurderSystem : GenericPersistence
 
     public static TimeSpan LongTermMurderDuration => _longTermMurderDuration;
 
+    public static bool PingPongEnabled => Core.T2A && !Core.LBR;
+
     public static void Configure()
     {
         _shortTermMurderDuration = ServerConfiguration.GetOrUpdateSetting("murderSystem.shortTermMurderDuration", TimeSpan.FromHours(8));
@@ -94,8 +96,11 @@ public class PlayerMurderSystem : GenericPersistence
         }
         else
         {
-            _murderContexts.Remove(pm);
             _contextTerms.Remove(context);
+            if (context.CanRemove())
+            {
+                _murderContexts.Remove(pm);
+            }
         }
     }
 
@@ -109,7 +114,7 @@ public class PlayerMurderSystem : GenericPersistence
         context.DecayKills();
         _contextTerms.Remove(context);
 
-        if (pm.Kills <= 0 && context.ShortTermMurders <= 0)
+        if (context.CanRemove())
         {
             _murderContexts.Remove(pm);
         }
@@ -168,6 +173,13 @@ public class PlayerMurderSystem : GenericPersistence
         return context;
     }
 
+    public static void ManuallySetPingPong(PlayerMobile player, int pingPong)
+    {
+        var context = GetOrCreateMurderContext(player);
+        context.PingPong = Math.Max(pingPong, 0);
+        UpdateMurderContext(context);
+    }
+
     public static void ManuallySetShortTermMurders(PlayerMobile player, int shortTermMurders)
     {
         var context = GetOrCreateMurderContext(player);
@@ -183,6 +195,11 @@ public class PlayerMurderSystem : GenericPersistence
         context.ShortTermMurders++;
         player.Kills++;
 
+        if (PingPongEnabled && player.Kills == 5)
+        {
+            context.PingPong++;
+        }
+
         context.ResetKillTime();
         UpdateMurderContext(context);
     }
@@ -193,7 +210,10 @@ public class PlayerMurderSystem : GenericPersistence
 
         if (!context.CheckStart())
         {
-            _murderContexts.Remove(player);
+            if (context.CanRemove())
+            {
+                _murderContexts.Remove(player);
+            }
             _contextTerms.Remove(context);
         }
         else if (player.NetState != null)
@@ -202,6 +222,50 @@ public class PlayerMurderSystem : GenericPersistence
         }
     }
 
+    internal static void ReportKillsToSelf(PlayerMobile player)
+    {
+        if (Core.Expansion == Expansion.None)
+        {
+            return;  // no consider sins in pre-t2a
+        }
+        else if (Core.Expansion is Expansion.T2A)
+        {
+            if (player.ShortTermMurders >= 5)
+            {
+                player.SendLocalizedMessage(502126, "", 0x022); // If thou should return to the land of the living, the innocent shall wreak havoc upon thy soul
+            }
+            else if (PingPongEnabled && player.Murderer)
+            {
+                player.SendLocalizedMessage(502123, "", 0x022);  // Thou art known throughout the land as a murderous brigand.
+            }
+            else if (player.ShortTermMurders > 0)
+            {
+                player.SendLocalizedMessage(502125, "", 0x59); // Although thou hast slain the innocent, thy deeds shall not bring retribution upon thy return to the living
+            }
+            else if (player.Kills > 0)
+            {
+                player.SendLocalizedMessage(502124, "", 0x59);  // Fear not, thou hast not slain the innocent in some time...
+            }
+            else  // no kills
+            {
+                player.SendLocalizedMessage(502122, "", 0x59);  // Fear not, thou hast not slain the innocent.
+            }
+        }
+        else if (!Core.SE)
+        {
+            player.SendMessage($"Short Term Murders : {player.ShortTermMurders}");
+            player.SendMessage($"Long Term Murders : {player.Kills}");
+            if (PingPongEnabled)
+            {
+                player.SendMessage($"Ping Pongs: {player.PingPong}");
+            }
+        }
+        else
+        {
+            player.SendLocalizedMessage(1114370, $"{player.ShortTermMurders}\t{player.Kills}");
+        }
+    }
+
     private class MurdererTimer : Timer
     {
         public MurdererTimer() : base(TimeSpan.FromMinutes(5.0), TimeSpan.FromMinutes(5.0))
@@ -233,9 +297,14 @@ public class PlayerMurderSystem : GenericPersistence
 
             while (queue.Count > 0)
             {
-                if (_murderContexts.Remove((PlayerMobile)queue.Dequeue(), out var context))
+                var pm = (PlayerMobile)queue.Dequeue();
+                if (_murderContexts.TryGetValue(pm, out var ctx))
                 {
-                    _contextTerms.Remove(context);
+                    if (ctx.CanRemove())
+                    {
+                        _murderContexts.Remove(pm);
+                    }
+                    _contextTerms.Remove(ctx);
                 }
             }
         }