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/core/providers/board_provider.dart

@@ -0,0 +1,16 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../../data/repositories/board_repositories.dart';
+import '../../view_models/board_view_model.dart';
+
+/// Lazy BoardViewModel provider
+/// Wraps screens that need BoardViewModel
+Widget boardProvider({required Widget child}) {
+  return ChangeNotifierProvider(
+    create:
+        (context) =>
+            BoardViewModel(boardRepository: context.read<BoardRepository>()),
+    child: child,
+  );
+}