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/ApiCallsBuilder.cs

@@ -1,7 +1,10 @@
 // ApiCallsBuilder.cs
+
+using System;
+using System.Collections.Generic;
 using System.Net;
 
-namespace Beam {
+namespace Beam.Api;
     /// <summary>
     /// Fluent builder for <see cref="ApiCalls"/>.
     /// </summary>
@@ -43,5 +46,4 @@ namespace Beam {
                 throw new InvalidOperationException("At least one ApiCall is required.");
             return new ApiCalls(_calls, _parallelism);
         }
-    }
-}
+    }