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/infrastructure/DigitalData.TaskFlow.Infrastructure/Persistence/Models/WorkflowListingReadModel.cs

@@ -17,7 +17,7 @@ public sealed class WorkflowListingReadModel
     /// Gets or sets the profile identifier.
     /// </summary>
     [Column("profileid")]
-    public int ProfileId { get; set; }
+    public byte ProfileId { get; set; }
 
     /// <summary>
     /// Gets or sets the voucher type.
@@ -53,7 +53,7 @@ public sealed class WorkflowListingReadModel
     /// Gets or sets the client number.
     /// </summary>
     [Column("mandantnr")]
-    public int ClientNumber { get; set; }
+    public short ClientNumber { get; set; }
 
     /// <summary>
     /// Gets or sets the client name.
@@ -101,7 +101,7 @@ public sealed class WorkflowListingReadModel
     /// Gets or sets the priority.
     /// </summary>
     [Column("priority")]
-    public int Priority { get; set; }
+    public byte Priority { get; set; }
 
     /// <summary>
     /// Gets or sets the source group text.