F6: Verify Gradio demo Space functional end-to-end

[AbdelStark]

Context

The demo Space at https://huggingface.co/spaces/abdelstark/lewm-rs-demo was updated to Gradio sdk_version 5.33.0 and the app was fixed to auto-detect action_dim and download .data files. Functional state has not been verified since the sdk version bump.

After F1 exports the full-training ONNX artifacts, the Space's model path may need updating to point at onnx-full/tract-compat/ instead of the short-run artifacts.

Work

1. Open https://huggingface.co/spaces/abdelstark/lewm-rs-demo — verify it loads (green status)
2. Run a CEM planning episode end-to-end via the UI
3. Confirm visualization renders (matplotlib figure or video)
4. If Space errors, check logs and patch app.py to fix model path or dependency issues
5. After F1 is done: update the Hub path in app.py to the full-training ONNX

Acceptance

• Space is green (no build errors)
• CEM planning demo works end-to-end with a sample episode
• Model path points at full-training ONNX artifacts (after F1)
• Space description updated with success rate once F2 is done