Add advanced sync logging for debugging host-client sync issues

- Add LogSync() helper method in Main.cs for consistent sync logging
- Log all packet send/receive events in PacketHandler and Packet classes
- Add detailed building placement logging in WorldPlace.cs (all properties, final state)
- Add building state update logging in BuildingStatePacket.cs
- Add building state send logging in BuildingStateManager.cs

All sync logs are prefixed with [SYNC] for easy filtering.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Packets/Packet.cs

@@ -38,6 +38,7 @@ namespace KCM.Packets
         {
             try
             {
+                Main.LogSync($"SEND TO ALL: {this.GetType().Name} (id={packetId}) except={exceptToClient}");
                 if (exceptToClient == 0)
                 {
                     if (KCServer.IsRunning)
@@ -75,6 +76,7 @@ namespace KCM.Packets
         {
             try
             {
+                Main.LogSync($"SEND: {this.GetType().Name} (id={packetId}) to={toClient} myId={KCClient.client?.Id}");
                 if (KCClient.client.IsConnected && toClient == 0)
                 {
                     this.clientId = KCClient.client.Id;