refactor: adapt current steering api changes, add deserialization test

schemas/openapi-steering.json

src/aura_engine/scheduling/api.py

src/aura_steering_api/models/__init__.py

src/aura_steering_api/models/playout_episode.py

src/aura_steering_api/models/playout_program_entry.py

src/aura_steering_api/models/playout_schedule.py

src/aura_steering_api/models/playout_show.py

src/aura_steering_api/models/time_slot.py

tests/json/steering-api-v1-program-playout.json

tests/test_scheduling_api_steering.py