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.Api/ApiCalls.cs

@@ -1,9 +1,15 @@
 // ApiCalls.cs
+
+using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
 using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 
-namespace Beam {
+namespace Beam.Api;
     /// <summary>
     /// Executes a batch of <see cref="ApiCall"/>s using either sequential or parallel strategy.
     /// </summary>
@@ -45,4 +51,4 @@ namespace Beam {
             return bag.OrderBy(x => x.idx).Select(x => x.res).ToList();
         }
     }
-}
+