Add dividendOfRange parameter to FunctionSlider and related components for improved range handling

lib/pages/routines/widgets/function_slider.dart

@@ -2,25 +2,34 @@ import 'package:flutter/material.dart';
 
 class FunctionSlider extends StatelessWidget {
   final dynamic initialValue;
-
   final (double min, double max) range;
   final void Function(double value) onChanged;
+  final double dividendOfRange;
 
   const FunctionSlider({
     required this.onChanged,
     required this.initialValue,
     required this.range,
+    required this.dividendOfRange,
     super.key,
   });
 
   @override
   Widget build(BuildContext context) {
+    final (min, max) = range;
+    final bool isValidRange = max > min;
+    final double value = initialValue is int
+        ? (initialValue as int).toDouble()
+        : (initialValue as double);
+
+    final int? divisions = isValidRange ? ((max - min) / dividendOfRange).round() : null;
+
     return Slider(
-      value: initialValue is int ? initialValue.toDouble() : range.$1,
-      min: range.$1,
-      max: range.$2,
-      divisions: (range.$2 - range.$1).toInt(),
-      onChanged: onChanged,
+      value: value.clamp(min, max),
+      min: min,
+      max: max,
+      divisions: divisions,
+      onChanged: isValidRange ? onChanged : null,
     );
   }
 }