Rebrand project: DocumentOperator to DocumentService

This commit implements a complete rebranding of the project:
- Updated all namespaces from `DocumentOperator` to `DocumentService`.
- Renamed file paths, embedded resources, and test data references.
- Updated configuration keys, logging paths, and Redis instance names.
- Revised documentation to reflect the new project name.
- Modified project and solution files to align with the new structure.
- Updated class names, DTOs, commands, queries, and handlers.
- Adjusted middleware, controllers, and API endpoints.
- Updated Swagger metadata and API titles to `DocumentService API`.
- Refactored test namespaces, resource paths, and embedded resources.
- Updated build and deployment configurations for the new name.
- Replaced all references to `DocumentOperator` in comments and literals.

These changes ensure consistency across the codebase and documentation.

DocumentOperator.Tests/Unit/Infrastructure/Services/PdfProcessing/DevExpressPdfProcessorTests.cs

@@ -1,11 +1,11 @@
 using System.Reflection;
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.Common.Interfaces;
-using DocumentOperator.Domain.Common.Exceptions;
-using DocumentOperator.Infrastructure.Services.PdfProcessing;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Domain.Common.Exceptions;
+using DocumentService.Infrastructure.Services.PdfProcessing;
 using FluentAssertions;
 
-namespace DocumentOperator.Tests.Unit.Infrastructure.Services.PdfProcessing;
+namespace DocumentService.Tests.Unit.Infrastructure.Services.PdfProcessing;
 
 /// <summary>
 /// Unit tests for DevExpressPdfProcessor.
@@ -31,7 +31,7 @@ public class DevExpressPdfProcessorTests
     private static byte[] LoadTestPdf(string filename)
     {
         var assembly = Assembly.GetExecutingAssembly();
-        var resourceName = $"DocumentOperator.Tests.TestData.Pdfs.{filename}";
+        var resourceName = $"DocumentService.Tests.TestData.Pdfs.{filename}";
 
         using var stream = assembly.GetManifestResourceStream(resourceName);