Refactor: rename BottomNavigation and update TendersScreen structure

- Renamed BottomNavigation to TenderBottomNavigation for clarity.
- Updated TendersScreen to use TenderBottomNavigation.
- Converted TendersScreen from StatelessWidget to StatefulWidget to manage tab state.
- Added TabController for handling tab changes and improved layout with SafeArea and PageView.

lib/views/tenders/widgets/last_tenders_tab.dart

@@ -0,0 +1,10 @@
+import 'package:flutter/material.dart';
+
+class LastTendersTab extends StatelessWidget {
+  const LastTendersTab({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(color: Colors.blue);
+  }
+}