I want an existing NodeGraph instance to support file-backed session persistence with current session() …

I want an existing NodeGraph instance to support file-backed session persistence with current session() …: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). load session(file path) should strip the path, raise IOError with file does not exist: <path when the file is…

The task

`load_session(file_path)` should strip the path, raise `IOError` with `file does not exist: <path>` when the file is missing, clear the current graph, then read that JSON file into the graph as a fresh session with the undo stack cleared. `import_session(file_path, clear_undo_stack=True)` should also strip and…

Part of FineEnvs/MiMo-V2.6-RL-harbor-code.