feat: Refactor code structure and optimize performance across multiple modules

mobile-apps/staff-app/lib/features/shifts/data/models/position.dart

@@ -0,0 +1,30 @@
+import 'package:json_annotation/json_annotation.dart';
+import 'package:krow/features/shifts/data/models/business_skill.dart';
+import 'package:krow/features/shifts/data/models/event_shift.dart';
+
+part 'position.g.dart';
+
+@JsonSerializable(fieldRename: FieldRename.snake)
+class Position {
+  String? id;
+  String? startTime;
+  String? endTime;
+  Shift? shift;
+  BusinessSkill? businessSkill;
+  double? rate;
+  @JsonKey(name: 'break')
+  int? breakMinutes;
+
+  Position({
+    this.id,
+    this.startTime,
+    this.endTime,
+    this.shift,
+    this.businessSkill,
+  });
+
+  factory Position.fromJson(Map<String, dynamic> json) =>
+      _$PositionFromJson(json);
+
+  Map<String, dynamic> toJson() => _$PositionToJson(this);
+}