Add board service and repository, update routes and assets

- Introduced BoardService and BoardRepository for managing board-related data.
- Updated app routes to reflect the new board screen structure.
- Added new board-related assets to the asset manager.
- Refactored BoardScreen navigation to utilize the new provider structure.

lib/view_models/board_view_model.dart

@@ -0,0 +1,77 @@
+import 'package:flutter/material.dart';
+
+import '../core/enums/task_status.dart';
+import '../core/utils/result.dart';
+import '../data/repositories/board_repositories.dart';
+import '../data/services/model/board_response/board_response.dart';
+
+class BoardViewModel with ChangeNotifier {
+  final BoardRepository _boardRepository;
+  BoardViewModel({required BoardRepository boardRepository})
+    : _boardRepository = boardRepository;
+
+  bool _isLoading = false;
+  String? _errorMessage;
+  List<BoardData> _boardData = [];
+
+  bool get isLoading => _isLoading;
+  String? get errorMessage => _errorMessage;
+  List<BoardData> get boardData => _boardData;
+  bool get hasData => _boardData.isNotEmpty;
+
+  Future<void> getBoard() async {
+    _isLoading = true;
+    notifyListeners();
+
+    final result = await _boardRepository.getBoard();
+
+    switch (result) {
+      case Ok<BoardResponse>():
+        // تبدیل به لیست قابل تغییر
+        _boardData = List.from(result.value.data ?? []);
+        break;
+      case Error<BoardResponse>():
+        _errorMessage = result.error.toString();
+        break;
+    }
+    _isLoading = false;
+    notifyListeners();
+  }
+
+  // update task status
+  void updateTaskStatus(String taskId, String newStatus) {
+    final taskIndex = _boardData.indexWhere((task) => task.id == taskId);
+    if (taskIndex != -1) {
+      _boardData[taskIndex] = _boardData[taskIndex].copyWith(status: newStatus);
+      notifyListeners();
+    }
+  }
+
+  bool isValidMove(TaskStatus currentStatus, TaskStatus targetStatus) {
+    if (currentStatus == TaskStatus.toDo) {
+      return targetStatus == TaskStatus.inProgress;
+    } else if (currentStatus == TaskStatus.inProgress) {
+      return targetStatus == TaskStatus.toDo || targetStatus == TaskStatus.done;
+    } else if (currentStatus == TaskStatus.done) {
+      return targetStatus == TaskStatus.inProgress;
+    }
+    return false;
+  }
+
+  List<BoardData> getTasksByStatus(TaskStatus status) {
+    return boardData.where((task) => task.status == status.value).toList();
+  }
+
+  void _updateTaskStatus(BoardData task, TaskStatus newStatus) {
+    if (task.status == newStatus.value) {
+      return;
+    }
+
+    final oldStatus = task.status;
+
+    // update task status in ViewModel
+    updateTaskStatus(task.id!, newStatus.value);
+
+    // _showStatusChangeMessage(context, task, oldStatus, newStatus);
+  }
+}