refactor: update function handling in routine dialogs

lib/pages/routines/widgets/routine_dialogs/water_heater/water_heater_presence_sensor.dart

@@ -188,9 +188,18 @@ class _WaterHeaterDialogRoutinesState extends State<WaterHeaterDialogRoutines> {
       onCancel: () => Navigator.pop(context),
       onConfirm: state.addedFunctions.isNotEmpty
           ? () {
+              final selectedFunctionData = state.addedFunctions.firstWhere(
+                (f) => f.functionCode == state.selectedFunction,
+                orElse: () => DeviceFunctionData(
+                  entityId: '',
+                  functionCode: state.selectedFunction ?? '',
+                  operationName: '',
+                  value: null,
+                ),
+              );
               context.read<RoutineBloc>().add(
                     AddFunctionToRoutine(
-                      state.addedFunctions,
+                      [selectedFunctionData],
                       widget.uniqueCustomId!,
                     ),
                   );