Add space heaters (#25250)

Content.Shared/Atmos/Visuals/SpaceHeaterVisuals.cs

@@ -0,0 +1,27 @@
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.Atmos.Visuals;
+
+/// <summary>
+///     Used for the visualizer
+/// </summary>
+[Serializable, NetSerializable]
+public enum SpaceHeaterVisualLayers : byte
+{
+    Main
+}
+
+[Serializable, NetSerializable]
+public enum SpaceHeaterVisuals : byte
+{
+    State,
+}
+
+[Serializable, NetSerializable]
+public enum SpaceHeaterState : byte
+{
+    Off,
+    StandBy,
+    Heating,
+    Cooling,
+}