fix(CS): send crown shield packet (0xB2/0x16) only on change, not every tick

The shield packet pops a modal message box on the client; sending it every tick
re-opened the modal continuously and froze player input at siege start. Track the
shield state in the context and only push the packet when it actually flips.

src/GameLogic/PlugIns/PeriodicTasks/CastleSiegeEventPlugIn.cs

@@ -428,7 +428,12 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
                 return;
             }
 
-            await player.InvokeViewPlugInAsync<ICastleSiegeStatusViewPlugIn>(p => p.SetCrownShieldAsync(crown.ShieldDown)).ConfigureAwait(false);
+            // Only tell the client when the shield state actually flips — the 0xB2/0x16 packet pops a modal
+            // message box, so sending it every tick would block player input.
+            if (crown.ShieldChanged)
+            {
+                await player.InvokeViewPlugInAsync<ICastleSiegeStatusViewPlugIn>(p => p.SetCrownShieldAsync(crown.ShieldDown)).ConfigureAwait(false);
+            }
 
             switch (crown.Event)
             {