Add Robotics tag and metadata

Hi! I'm VB from Hugging Face. Congratulations on your model! I'm opening a quick PR to update the model card to add Robotics metadata.

This PR adds standard Robotics metadata to the model card:
- Added 'Robotics' to tags
- Set pipeline_tag to 'robotics'

These changes help improve discoverability of robotics-related models on the Hugging Face Hub.

README.md

@@ -1,4 +1,3 @@
-
 ---
 tags:
 - phosphobot
@@ -40,4 +39,4 @@ More:
 
 - 🤖 **Get your robot**: [robots.phospho.ai](https://robots.phospho.ai?utm_source=replicate)
 
-- 🔗 **Explore on Replicate**: [Replicate](https://replicate.com/phospho-app/gr00t-policy)
+- 🔗 **Explore on Replicate**: [Replicate](https://replicate.com/phospho-app/gr00t-policy)