Add delay between calling C-STORE and updating worklist item status

There's a possible race condition where the C-STORE command updates the
worklist item to IN PROGRESS after we attempt to move it to COMPLETED.

Author: steventux

src/modality_emulator.py

@@ -154,6 +154,8 @@ def process_worklist_items(self, ae: AE):
                             )
                             series_number += 1
 
+                    time.sleep(1)  # Allow C-STORE operations to complete before updating status
+
                     self.mwl_storage.update_status(accession_number, MWLStatus.COMPLETED.value)
                     logger.info(f"Completed processing for worklist item {accession_number}")
                 elif status_code == SUCCESS: