This PR improves the model card for FlowWAM by:
- Linking it to the paper on Hugging Face: [FlowWAM: Optical Flow as a Unified Action Representation for World Action Models](https://huggingface.co/papers/2607.13017).
- Adding the link to the official project page: https://flow-wam.github.io/.
- Including the BibTeX citation from the paper.
Add model card (RoboTwin flow-action IDM checkpoint + inference config)
