Refactor workflows and improve API responses

- Added `BackToPerMethodId` constant and updated validation rules in `CloseWorkflowCommandValidator`.
- Refactored `GetWorkflowsQueryHandler` for simpler `hasListingData` logic.
- Replaced strongly-typed properties with `JsonElement` in `ContractsSourceBlock` and `FerdinandSourceBlock`.
- Updated `WorkflowListingReadModel` to use smaller data types for efficiency.
- Refactored `WorkflowRepository` to use JSON-based data retrieval and parsing.
- Introduced `MetaOnlyResponse` and `WorkflowsResponse` for consistent API responses.
- Updated `DocumentsController` and `WorkflowsController` to use new response types.
- Added `ApiKeyAuthMiddleware` for API key validation and integrated it into the middleware pipeline.
- Refactored `ExceptionHandlingMiddleware` to use `MetaOnlyResponse` for error handling.
- Performed general cleanup and modernization for improved readability and maintainability.

src/presentation/DigitalData.TaskFlow.API/Controllers/DocumentsController.cs

@@ -1,4 +1,5 @@
 using DigitalData.TaskFlow.Application.Features.Documents.Queries.GetDocument;
+using DigitalData.TaskFlow.API.Contracts.Common;
 using DigitalData.TaskFlow.Domain.Common;
 using DigitalData.TaskFlow.Domain.Documents;
 using MediatR;
@@ -21,9 +22,11 @@ public sealed class DocumentsController(ISender sender) : ControllerBase
     /// <returns>Binary stream when available.</returns>
     [HttpGet("{id}")]
     [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
-    [ProducesResponseType(typeof(ApiEnvelope<object>), StatusCodes.Status400BadRequest)]
-    [ProducesResponseType(typeof(ApiEnvelope<object>), StatusCodes.Status404NotFound)]
-    [ProducesResponseType(typeof(ApiEnvelope<object>), StatusCodes.Status500InternalServerError)]
+    [ProducesResponseType(typeof(MetaOnlyResponse), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(MetaOnlyResponse), StatusCodes.Status401Unauthorized)]
+    [ProducesResponseType(typeof(MetaOnlyResponse), StatusCodes.Status403Forbidden)]
+    [ProducesResponseType(typeof(MetaOnlyResponse), StatusCodes.Status404NotFound)]
+    [ProducesResponseType(typeof(MetaOnlyResponse), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> GetAsync([FromRoute] string id, CancellationToken cancellationToken)
     {
         var response = await sender.Send(new GetDocumentQuery(id), cancellationToken);