sample json fix

lib/screens/deck_import_screen.dart

@@ -348,6 +348,7 @@ class _DeckImportScreenState extends State<DeckImportScreen> {
           'prompt': 'Sample Question $i?',
           'answers': ['Answer A', 'Answer B', 'Answer C', 'Answer D'],
           'correctAnswerIndices': [i % 4],
+          if (i == 0) 'explanation': 'Optional explanation shown when viewing question details after an attempt.',
           'isKnown': i < 5,
         };
       }),
@@ -502,32 +503,24 @@ class _DeckImportScreenState extends State<DeckImportScreen> {
                 child: Column(
                   crossAxisAlignment: CrossAxisAlignment.stretch,
                   children: [
-                    Row(
-                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    Wrap(
+                      spacing: 8,
+                      runSpacing: 4,
                       children: [
-                        Text(
-                          'Deck JSON',
-                          style: Theme.of(context).textTheme.titleMedium,
+                        TextButton.icon(
+                          onPressed: _pickJsonFile,
+                          icon: const Icon(Icons.folder_open, size: 20),
+                          label: const Text('Select file'),
+                        ),
+                        TextButton.icon(
+                          onPressed: _loadSampleDeck,
+                          icon: const Icon(Icons.description, size: 20),
+                          label: const Text('Load Sample'),
                         ),
-                        Row(
-                          mainAxisSize: MainAxisSize.min,
-                          children: [
-                            TextButton.icon(
-                              onPressed: _pickJsonFile,
-                              icon: const Icon(Icons.folder_open),
-                              label: const Text('Select file'),
-                            ),
-                            TextButton.icon(
-                              onPressed: _loadSampleDeck,
-                              icon: const Icon(Icons.description),
-                              label: const Text('Load Sample'),
-                            ),
-                            IconButton(
-                              onPressed: _copyFieldToClipboard,
-                              icon: const Icon(Icons.copy),
-                              tooltip: 'Copy field contents',
-                            ),
-                          ],
+                        IconButton(
+                          onPressed: _copyFieldToClipboard,
+                          icon: const Icon(Icons.copy),
+                          tooltip: 'Copy field contents',
                         ),
                       ],
                     ),