add promotion/detail

lib/features/main/presentation/providers/current_page_provider.dart

@@ -0,0 +1,30 @@
+/// Provider: Current Page Index Provider
+///
+/// Manages the state of the current bottom navigation page index.
+library;
+
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'current_page_provider.g.dart';
+
+/// Current Page Index Notifier
+///
+/// Manages which page is currently displayed in the bottom navigation.
+/// Pages:
+/// - 0: Home
+/// - 1: Loyalty
+/// - 2: Promotions
+/// - 3: Notifications
+/// - 4: Account
+@riverpod
+class CurrentPageIndex extends _$CurrentPageIndex {
+  @override
+  int build() => 0;
+
+  /// Set the current page index
+  void setIndex(int index) {
+    if (index >= 0 && index <= 4) {
+      state = index;
+    }
+  }
+}