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/Integration/API/PdfAttachmentControllerTests.cs

@@ -1,12 +1,12 @@
-using DocumentOperator.API.Controllers; // For CheckPdfAttachmentsRequest DTO
-using DocumentOperator.Application.Common.DTOs;
+using DocumentService.API.Controllers; // For CheckPdfAttachmentsRequest DTO
+using DocumentService.Application.Common.DTOs;
 using FluentAssertions;
 using Microsoft.AspNetCore.Mvc.Testing;
 using System.Net;
 using System.Net.Http.Json;
 using Xunit;
 
-namespace DocumentOperator.Tests.Integration.API;
+namespace DocumentService.Tests.Integration.API;
 
 /// <summary>
 /// Integration tests for PdfAttachmentController.
@@ -31,7 +31,7 @@ public class PdfAttachmentControllerTests : IClassFixture<WebApplicationFactory<
     private static async Task<byte[]> LoadTestPdfAsync(string filename)
     {
         var assembly = typeof(PdfAttachmentControllerTests).Assembly;
-        var resourceName = $"DocumentOperator.Tests.TestData.Pdfs.{filename}";
+        var resourceName = $"DocumentService.Tests.TestData.Pdfs.{filename}";
 
         using var stream = assembly.GetManifestResourceStream(resourceName);
         if (stream == null)