style(download): 补全条件分支花括号

lib/core/data/services/download_controller.dart

@@ -120,7 +120,9 @@ class DownloadController extends ChangeNotifier {
     String episodeId, {
     DownloadLicense? license,
   }) async {
-    if (_downloading.contains(episodeId)) return const DownloadActionResult(ok: true);
+    if (_downloading.contains(episodeId)) {
+      return const DownloadActionResult(ok: true);
+    }
     final source = license ?? _licenseFor(episodeId);
     if (source == null) return const DownloadActionResult(ok: false);
     _beginDownload(episodeId);
@@ -129,7 +131,8 @@ class DownloadController extends ChangeNotifier {
       final media = await _storage.download(
         episodeId: episodeId,
         url: resolved,
-        onProgress: (received, total) => _onProgress(episodeId, received, total),
+        onProgress: (received, total) =>
+            _onProgress(episodeId, received, total),
       );
       _localPaths[episodeId] = media.filePath;
       _progress[episodeId] = 1;