fix: resolve 3 console errors (RenderFlex overflow, gamification 404s, CORS)

- Wrap Top Events skeleton Row in SingleChildScrollView to fix 225px
  RenderFlex overflow when 3x 200px skeletons exceed container width
- Fix gamification service using POST for GET endpoints: dashboard,
  leaderboard, and shop/items all use router.get() on the Node.js server
- CORS: add http://localhost:8080 to CORS_ALLOWED_ORIGINS (applied live
  to eventify-django container + local settings.py)

lib/screens/home_screen.dart

@@ -1590,7 +1590,10 @@ class _HomeScreenState extends State<HomeScreen> with SingleTickerProviderStateM
           SizedBox(
             height: 200,
             child: _allFilteredByDate.isEmpty && _loading
-                ? Row(children: List.generate(3, (_) => const Padding(padding: EdgeInsets.only(right: 12), child: EventCardSkeleton())))
+                ? SingleChildScrollView(
+                    scrollDirection: Axis.horizontal,
+                    child: Row(children: List.generate(3, (_) => const Padding(padding: EdgeInsets.only(right: 12), child: EventCardSkeleton()))),
+                  )
                 : _allFilteredByDate.isEmpty
                     ? Center(child: Text(
                         _selectedDateFilter.isNotEmpty ? 'No events for "$_selectedDateFilter"' : 'No events found',