Fix maintenance deployment locking and failure recovery

Hold the instance lock across CLS cleanup, migration and deployment, and persist maintenance phases for safe retries. Keep stopped deployments stopped during recovery and unpause the trader after preparation failures.

scripts/tests/test_instance.py

@@ -137,7 +137,7 @@ class EntrypointTests(unittest.TestCase):
 
     def test_pending_and_shared_lock(self):
         pending = self.directory / 'deployment.pending.json'
-        pending.write_text('{}')
+        pending.write_text('{"operation":"remove-cls","phase":"cleanup"}')
         self.assertEqual(self.invoke(code=1), [])
         calls = self.invoke('stop')
         self.assertEqual(calls[-1]['args'][-1], 'stop')