Refactor data providers and update abstractions

- Removed obsolete data providers: `AnchorCollectionDataProvider`, `ContentsDataProvider`, and others, consolidating logic into new composable providers.
- Added `ComposeDataProviders`, `SelectDataProvider`, and `RelationalDataProvider` for improved flexibility and reusability.
- Introduced `IManySelectionComposableDataProvider` interface to support multiple-node selection.
- Enhanced `UnitDownloader` with more robust progress tracking.
- Updated package references and project dependencies for consistency.
- Improved error handling in `StealthConfig` initialization for better fallback on browser drivers.
- Incremented project version to 2.4.5.

Beam.Downloaders/UnitDownloader.cs

@@ -28,12 +28,22 @@ namespace Beam.Downloaders {
             byte[] buffer = new byte[bufferSize];
             int inBuffer = 0;
             long downloaded = 0;
+
+            long? remaining() {
+                try {
+                    return stream.Length - downloaded;
+                }
+                catch {
+                    return null;
+                }
+            }   
+            
             while ((inBuffer = stream.Read(buffer)) > 0) {
                 downloaded += inBuffer;
                 await destinationStream.WriteAsync(buffer.AsMemory(0, inBuffer), ct);
                 progress?.Report(new DownloadReport() {
                     BytesDownloaded = inBuffer,
-                    BytesRemaining = stream.Length - downloaded 
+                    BytesRemaining = remaining()
                 });
                 
                 ct.ThrowIfCancellationRequested();