Add liked tenders functionality to HomeRepository and ViewModel

- Integrated LikedTendersService into HomeRepository to fetch the count of user-liked tenders.
- Updated HomeViewModel to load and manage the userLikedTendersCount.
- Adjusted UI components across home pages to display the liked tenders count.
- Refactored date handling in date_utils.dart to improve timestamp parsing and validation.
- Enhanced unit tests for date utilities to cover new edge cases.

lib/views/detail/widgets/deadline_item.dart

@@ -19,6 +19,9 @@ class DeadlineItem extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    if (detail.submissionDeadline == null && detail.applicationDeadline == null) {
+      return const SizedBox.shrink();
+    }
     return isScreenBig
         ? Padding(
           padding: const EdgeInsets.symmetric(vertical: 0),