Add FunctionType enum and ValueModel class

- Added FunctionType enum with values Boolean, Enum, Integer, Raw, String.
- Introduced ValueModel class to handle unit, min, max, scale, and step values
  for functions in FunctionModel.

lib/features/devices/model/function_model.dart

@@ -1,7 +1,9 @@
+import 'package:syncrow_app/utils/resource_manager/constants.dart';
+
 class FunctionModel {
   String? code;
-  String? type;
-  String? values;
+  FunctionType? type;
+  ValueModel? values;
 
   FunctionModel({
     required this.code,
@@ -25,3 +27,41 @@ class FunctionModel {
     };
   }
 }
+
+//"values": "{\"unit\":\"\",\"min\":1,\"max\":10,\"scale\":0,\"step\":1}",
+
+class ValueModel {
+  String? unit;
+  int? min;
+  int? max;
+  int? scale;
+  int? step;
+
+  ValueModel({
+    required this.unit,
+    required this.min,
+    required this.max,
+    required this.scale,
+    required this.step,
+  });
+
+  factory ValueModel.fromJson(Map<String, dynamic> json) {
+    return ValueModel(
+      unit: json['unit'],
+      min: json['min'],
+      max: json['max'],
+      scale: json['scale'],
+      step: json['step'],
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'unit': unit,
+      'min': min,
+      'max': max,
+      'scale': scale,
+      'step': step,
+    };
+  }
+}