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/protected_router.py

@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends
 
 from app.routers.auth import get_current_user
 from app.routers.address import address_router
+from app.routers.beamtime import beamtime_router
 from app.routers.contact import contact_router
 from app.routers.shipment import shipment_router
 from app.routers.dewar import dewar_router
@@ -20,3 +21,6 @@ protected_router.include_router(
     shipment_router, prefix="/shipments", tags=["shipments"]
 )
 protected_router.include_router(dewar_router, prefix="/dewars", tags=["dewars"])
+protected_router.include_router(
+    beamtime_router, prefix="/beamtimes", tags=["beamtimes"]
+)