feat: UX-005 — Hero transitions, fade screen load, AnimatedList leaderboard stagger

lib/screens/contribute_screen.dart

@@ -14,6 +14,7 @@ import 'package:share_plus/share_plus.dart';
 import '../core/app_decoration.dart';
 import '../features/gamification/models/gamification_models.dart';
 import '../features/gamification/providers/gamification_provider.dart';
+import 'package:flutter_staggered_animations/flutter_staggered_animations.dart';
 import '../widgets/bouncing_loader.dart';
 import '../widgets/glass_card.dart';
 import '../widgets/landscape_section_header.dart';
@@ -2146,12 +2147,19 @@ class _ContributeScreenState extends State<ContributeScreen>
                   ),
                 ),
 
-                // Ranked list (rank 4+)
+                // Ranked list (rank 4+) with stagger animation
                 SliverList(
                   delegate: SliverChildBuilderDelegate(
                     (ctx, i) {
                       final entry = entries.length > 3 ? entries[i + 3] : entries[i];
-                      return _buildRankRow(entry);
+                      return AnimationConfiguration.staggeredList(
+                        position: i,
+                        duration: const Duration(milliseconds: 375),
+                        child: SlideAnimation(
+                          verticalOffset: 40.0,
+                          child: FadeInAnimation(child: _buildRankRow(entry)),
+                        ),
+                      );
                     },
                     childCount: entries.length > 3 ? entries.length - 3 : 0,
                   ),