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/views/shared/desktop_navigation_widget.dart

@@ -86,18 +86,21 @@ class DesktopNavigationWidget extends StatelessWidget {
           const SizedBox(width: 24),
           _navigationItem(
             context: context,
-            text: TendersStrings.contracts,
+            text: TendersStrings.board,
             isActive: currentIndex == 2,
             onTap: () {
               if (currentIndex == 2) {
                 return;
               } else {
-                //    Router.neglect(context, () => TendersRouteData().go(context));
+                Router.neglect(
+                  context,
+                  () => const BoardRouteData().go(context),
+                );
                 //    context.read<TendersViewModel>().getTenders();
               }
             },
-            iconPath: AssetsManager.contracts,
-            activeIconPath: AssetsManager.contracts,
+            iconPath: AssetsManager.board,
+            activeIconPath: AssetsManager.boardActive,
           ),
           const SizedBox(width: 24),
           _navigationItem(