Modal Product Updates: Notebooks, Sandbox Idle Timeouts, and Client Changes

Modal shipped product updates including Modal Notebooks for cloud-based Python experimentation with up to 8 B200 GPUs, plus an optional idle_timeout parameter for modal.Sandbox.create(). The client also added a startup_timeout parameter to @app.function() and @app.cls() decorators and a new API pattern for imperative management of Modal resource types. Modal Notebooks have since been shut down, though existing notebooks can still be downloaded as .ipynb files.