fix: use config singleton instance

src/aura_engine/app.py

src/aura_engine/base/config.py

src/aura_engine/core/channels.py

src/aura_engine/plugins/clock.py

src/aura_engine/plugins/monitor.py

src/aura_engine/scheduling/models.py

src/aura_engine/scheduling/programme.py

src/aura_engine/scheduling/scheduler.py

src/aura_engine/scheduling/utils.py