refactor: update daily challenge view test to use createTestWidget (#1656)

* Initial plan

* Update daily challenge view test to use createTestWidget

Co-authored-by: huyenltnguyen <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: huyenltnguyen <[email protected]>

Author: Copilot

mobile-app/test/widget/daily_challenge_view_test.dart

@@ -46,11 +46,7 @@ void main() {
     }
 
     testWidgets('should display app bar with correct title', (tester) async {
-      await tester.pumpWidget(
-        const MaterialApp(
-          home: DailyChallengeView(),
-        ),
-      );
+      await tester.pumpWidget(createTestWidget());
 
       await tester.pump();