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.

CONTROLLER_ENDPOINTS.md

@@ -1,4 +1,4 @@
-# DocumentOperator - Controller & Endpoint Specification
+# DocumentService - Controller & Endpoint Specification
 
 **Project:** DocumentService (DOC)  
 **Ticket:** DOC-1 - GDPicture and Nutrient Replacing  
@@ -9,7 +9,7 @@
 
 ## Overview
 
-This specification defines the controller structure and REST API endpoints for the DocumentOperator service.
+This specification defines the controller structure and REST API endpoints for the DocumentService service.
 
 ---
 
@@ -293,7 +293,7 @@ The service can be used on the client side **without manual HTTP response handli
 
 **Example Client SDK:**
 ```csharp
-var client = new DocumentOperatorClient("https://api.example.com");
+var client = new DocumentServiceClient("https://api.example.com");
 var result = await client.Pdf.Validation.ValidateAsync(pdfFile);
 if (result.IsValid) { ... }
 ```