Replaced Last with LastBatch in ReadResultViewQuery to enable fetching all results from the most recent batch. Updated handler logic and tests accordingly, and added GetLastBatchEntitiesAsync to retrieve entities by latest BatchId.
Added InvokeBatchDuplicateGuardTests to verify that invoking batch rec actions with an existing BatchId throws BadRequestException, while using a new BatchId does not trigger the duplicate guard. Tests use MediatR ISender and real database data for integration coverage. Added necessary using directives.
