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/core/utils/date_utils.dart

@@ -1,24 +1,33 @@
 import 'package:intl/intl.dart';
 
-/// Parses API date fields that may arrive as int, double, or string.
+/// Parses an API timestamp field that may arrive as int, double, or string.
+/// Returns null for missing, empty, unparseable, or non-positive values
+/// (a non-positive epoch is treated as "no value" by the API).
 int? unixTimestampFromJson(dynamic value) {
   if (value == null) return null;
-  if (value is int) return value;
-  if (value is num) return value.toInt();
-  if (value is String) {
+  int? parsed;
+  if (value is int) {
+    parsed = value;
+  } else if (value is num) {
+    parsed = value.toInt();
+  } else if (value is String) {
     final trimmed = value.trim();
     if (trimmed.isEmpty) return null;
-    return int.tryParse(trimmed);
+    parsed = int.tryParse(trimmed);
   }
-  return null;
+  if (parsed == null || parsed <= 0) return null;
+  return parsed;
 }
 
-/// Converts a Unix timestamp (seconds) from the API to a display string.
-/// Mirrors Next.js `unixToDate` using `moment.unix(unix)`.
+/// Converts a Unix timestamp from the API to a display string.
+///
+/// The API contract is seconds since epoch, but some legacy fields still
+/// emit milliseconds. Anything past the year 2286 in seconds (>1e10) is
+/// assumed to be milliseconds and converted down. Remove this branch once
+/// every endpoint has been migrated to seconds.
 String timeConvertor(int? unix, {bool hasTime = false}) {
-  if (unix == null || unix == 0) return '-';
+  if (unix == null || unix <= 0) return '-';
 
-  // Values above ~year 2286 in seconds are treated as milliseconds.
   final seconds = unix > 9999999999 ? unix ~/ 1000 : unix;
   final date = DateTime.fromMillisecondsSinceEpoch(
     seconds * 1000,