Add beamtime functionality to backend.

Introduce new endpoint and model for managing beamtimes, including shifts and user-specific access. Updated test scripts and data to reflect beamtime integration, along with minor fixes for job status enumeration and example notebook refinement.

backend/app/routers/sample.py

@@ -399,7 +399,7 @@ def update_experiment_run_dataset(
                 sample_id=sample_id,
                 run_id=run_id,
                 experiment_parameters=exp,  # adjust this line as appropriate
-                status=JobStatus.TODO,
+                status=JobStatus.TO_DO,
             )
             db.add(new_job)
             db.commit()