Add sequence numbers to server broadcasts and client state handling for out-of-order update detection.

cmd/client/connection_wasm.go

@@ -72,6 +72,13 @@ func (g *Game) connectToServer() {
 			payloadBytes, _ := json.Marshal(msg.Payload)
 			var state game.GameState
 			if err := json.Unmarshal(payloadBytes, &state); err == nil {
+				// Out-of-Order-Erkennung: Ignoriere alte Updates
+				if state.Sequence > 0 && state.Sequence <= g.lastRecvSeq {
+					// Alte Nachricht - ignorieren
+					return nil
+				}
+				g.lastRecvSeq = state.Sequence
+
 				// Server Reconciliation für lokalen Spieler (VOR dem Lock)
 				for _, p := range state.Players {
 					if p.Name == g.playerName {