fix：增加图片选择和拍照功能

lib/common/upload/upload_repository.dart

@@ -0,0 +1,20 @@
+import '../../features/assets/data/asset_models.dart';
+
+class UploadRepository {
+  const UploadRepository();
+
+  Future<UploadResult> uploadAssetImage(AssetImage image) async {
+    // TODO: Connect to upload backend.
+    return UploadResult(
+      remoteUrl: image.remoteUrl,
+      thumbnailUrl: image.thumbnailUrl,
+    );
+  }
+}
+
+class UploadResult {
+  const UploadResult({this.remoteUrl, this.thumbnailUrl});
+
+  final String? remoteUrl;
+  final String? thumbnailUrl;
+}