fix: add missing _get_container_info method to AsyncDockerClient

docker_service.get_container_info() was calling self._docker_client._get_container_info()
but AsyncDockerClient didn't have this method, causing silent AttributeError and
returning None, which triggered false health check failures.

Added _get_container_info() using aiodocker's container.show() to properly retrieve
container state information for health monitoring.

session-manager/async_docker_client.py

@@ -199,6 +199,23 @@ class AsyncDockerClient:
         except DockerError:
             return None
 
+    async def _get_container_info(self, container_id: str) -> Optional[Dict[str, Any]]:
+        """
+        Get detailed container information (equivalent to docker inspect).
+        
+        Returns the full container info dict including State, Config, etc.
+        """
+        try:
+            container = await self._docker.containers.get(container_id)
+            if container:
+                # show() returns the full container inspect data
+                return await container.show()
+        except DockerError as e:
+            logger.debug(f"Failed to get container info for {container_id}: {e}")
+        except Exception as e:
+            logger.debug(f"Unexpected error getting container info: {e}")
+        return None
+
     async def list_containers(
         self, all: bool = False, filters: Optional[Dict[str, Any]] = None
     ) -> List[DockerContainer]: