Add board navigation and assets

- Introduced new board-related assets in AssetsManager.
- Updated NetworkManager to increase connection and receive timeouts to 20 seconds.
- Added BoardRouteData for navigation to the BoardScreen.
- Updated app routes to include the new board route.
- Modified DesktopNavigationWidget to include a navigation item for the board.
- Added a new string constant for the board label in TendersStrings.

lib/core/routes/app_routes.g.dart

@@ -14,6 +14,7 @@ List<RouteBase> get $appRoutes => [
   $finalCompletionOfDocumentsRouteData,
   $completionOfDocumentsRouteData,
   $likedTendersRouteData,
+  $boardRouteData,
   $tenderDetailRouteData,
   $forgotPasswordRouteData,
   $forgotPasswordOtpRouteData,
@@ -353,6 +354,30 @@ mixin _$LikedTendersRouteData on GoRouteData {
   void replace(BuildContext context) => context.replace(location);
 }
 
+RouteBase get $boardRouteData =>
+    GoRouteData.$route(path: '/board', factory: _$BoardRouteData._fromState);
+
+mixin _$BoardRouteData on GoRouteData {
+  static BoardRouteData _fromState(GoRouterState state) =>
+      const BoardRouteData();
+
+  @override
+  String get location => GoRouteData.$location('/board');
+
+  @override
+  void go(BuildContext context) => context.go(location);
+
+  @override
+  Future<T?> push<T>(BuildContext context) => context.push<T>(location);
+
+  @override
+  void pushReplacement(BuildContext context) =>
+      context.pushReplacement(location);
+
+  @override
+  void replace(BuildContext context) => context.replace(location);
+}
+
 RouteBase get $tenderDetailRouteData => GoRouteData.$route(
   path: '/tender-detail',