feat: enhance EmptyStateView layout with positioned action button for better UX

flutter/lib/features/inventory/presentation/inventory_screen.dart

@@ -21,13 +21,19 @@ class InventoryScreen extends ConsumerWidget {
       ),
       data: (items) {
         if (items.isEmpty) {
-          return EmptyStateView(
+          return Stack(
-            title: 'Inventariet är tomt.',
+            children: [
-            action: FloatingActionButton.extended(
+              const EmptyStateView(title: 'Inventariet är tomt.'),
+              Positioned(
+                right: 16,
+                bottom: 16,
+                child: FloatingActionButton.extended(
                   onPressed: () => context.push('/inventory/create'),
                   icon: const Icon(Icons.add),
                   label: const Text('Lägg till'),
                 ),
+              ),
+            ],
           );
         }
         return Stack(