Improve model card: Add paper and code links

This PR enhances the model card by adding prominent links to the paper ([PIPer: On-Device Environment Setup via Online Reinforcement Learning](https://huggingface.co/papers/2509.25455)) and its GitHub repository ([https://github.com/JetBrains-Research/PIPer](https://github.com/JetBrains-Research/PIPer)).

These additions improve the discoverability and accessibility of key resources for the model. The existing metadata is correct and remains unchanged. No sample usage section has been added as no direct inference code was found in the provided GitHub README.

README.md

@@ -1,19 +1,22 @@
 ---
-library_name: transformers
+base_model:
+- JetBrains-Research/Qwen3-8B-am
 datasets:
 - JetBrains-Research/PIPer-envbench-zeroshot-rl
 - JetBrains-Research/PIPer-SFT-2500-sharegpt
-base_model:
-- JetBrains-Research/Qwen3-8B-am
-pipeline_tag: text-generation
+library_name: transformers
 license: mit
+pipeline_tag: text-generation
 ---
+
 <img src="https://github.com/JetBrains-Research/PIPer/blob/main/misc/piper-logo.png?raw=true" alt="PIPer Mascot" style="height: 6em">
 <h1>
   PIPer: On-Device Environment Setup via Online Reinforcement Learning
   
 </h1>
 
+[Paper](https://huggingface.co/papers/2509.25455) | [Code](https://github.com/JetBrains-Research/PIPer)
+
 <div align="center">
 
 [![Models](https://img.shields.io/badge/🤗%20Hugging%20Face-Models-orange.svg)](https://jb.gg/PIPer)
@@ -97,4 +100,4 @@ uv run piper/hparams_entrypoint.py +experiment=llm-reward --info config
 
 ## 📄 License
 
-This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.