refactor backend module architecture

tests/test_monitor_gap_recovery.py

@@ -4,12 +4,12 @@ from unittest.mock import MagicMock
 
 from watchfiles import Change
 
-from app.core.config import settings
+from app.platform.config import settings
 from app.monitor import LocalDirectoryWatcher, Monitor
 from app.monitor.dispatcher import TransferDispatcher
 from app.monitor.recovery import RecoveryExecutor
 from app.monitor.syslimits import decide_monitor_mode
-from app.utils.system import SystemUtils
+from app.infrastructure.system import SystemUtils
 
 
 def _build_monitor(handle_file: MagicMock = None):