Add Scene::PassMouseWheel

Client/include/Client/Scene.hpp

@@ -57,6 +57,8 @@ namespace CaveGame::Client
         /// @param pos The up-to-date mouse position.
         virtual void PassMouseMovement(const Vector2& pos) {}
 
+        virtual void PassMouseWheel(int wheel) {}
+
         /// Returns whether this scene is currently the "Active" scene.
         [[nodiscard]] bool Active() const;
     protected: