fix:保证json快照一致性

src/main/java/com/iflytop/handacid/app/core/state/DeviceState.java

@@ -46,7 +46,7 @@ public class DeviceState {
     @Schema(description = "当前登录用户")
     private volatile User currentUser;
 
-    public JSONObject toJSON() {
+    public synchronized JSONObject toJSON() {
         JSONObject json = new JSONObject();
         json.putOnce("channelState", new ArrayList<>(channelStateMap.values()));
         json.putOnce("mode", mode);