fix：增加图片选择和拍照功能

lib/common/upload/upload_service.dart

@@ -0,0 +1,13 @@
+import '../../features/assets/data/asset_models.dart';
+import 'upload_repository.dart';
+
+class UploadService {
+  const UploadService({required this.repository});
+
+  final UploadRepository repository;
+
+  Future<UploadResult> uploadAssetImage(AssetImage image) async {
+    // Placeholder: future implementation will upload the file and return URLs.
+    return repository.uploadAssetImage(image);
+  }
+}