Address PR review: custom typeRegistry test, CI Flutter version pin, example pubspec material design flag

.github/workflows/ci.yml

@@ -15,6 +15,7 @@ jobs:
 
       - uses: subosito/flutter-action@v2
         with:
+          flutter-version: '3.41.5'
           channel: stable
 
       - name: Install dependencies

example/pubspec.yaml

@@ -11,3 +11,6 @@ dependencies:
     sdk: flutter
   editorjs_flutter:
     path: ../
+
+flutter:
+  uses-material-design: true

test/unit/editor_controller_test.dart

@@ -253,11 +253,39 @@ void main() {
     });
 
     test('respects custom typeRegistry parameter', () {
-      // Using default registry — header should be parsed
       const json =
           '{"blocks":[{"type":"header","data":{"text":"Hi","level":1}}]}';
-      final ctrl = EditorController.fromJson(json);
+
+      // Custom registry that alters how header blocks are created
+      final customRegistry = BlockTypeRegistry()
+        ..register(_PrefixedHeaderMapper('Custom: '));
+
+      final ctrl = EditorController.fromJson(
+        json,
+        typeRegistry: customRegistry,
+      );
+
       expect(ctrl.blockCount, 1);
+      expect(ctrl.blocks.first, isA<HeaderBlock>());
+      final headerBlock = ctrl.blocks.first as HeaderBlock;
+      expect(headerBlock.text, 'Custom: Hi');
+      expect(headerBlock.level, 1);
     });
   });
 }
+
+/// A [BlockMapper] that prefixes header text — used to verify custom
+/// registries are respected by [EditorController.fromJson].
+class _PrefixedHeaderMapper implements BlockMapper<HeaderBlock> {
+  final String prefix;
+  const _PrefixedHeaderMapper(this.prefix);
+
+  @override
+  String get supportedType => 'header';
+
+  @override
+  HeaderBlock fromJson(Map<String, dynamic> data) => HeaderBlock(
+        text: '$prefix${data['text'] ?? ''}',
+        level: data['level'] is int ? data['level'] as int : 1,
+      );
+}