Add pipeline tag, paper link, and GitHub repository link

Hi,

This PR improves the model card by:
- Adding `pipeline_tag: feature-extraction` to the YAML metadata so the model is correctly categorized on the Hub.
- Adding links to the paper ([RiboSphere: Learning Unified and Efficient Representations of RNA Structures](https://huggingface.co/papers/2603.19636)) and official GitHub repository ([Zhangz312/RiboSphere](https://github.com/Zhangz312/RiboSphere)) in the main navigation section.

Best regards,
Niels

README.md

@@ -1,5 +1,6 @@
 ---
 library_name: pytorch
+pipeline_tag: feature-extraction
 tags:
 - rna
 - rna-structure
@@ -24,7 +25,7 @@ Discrete geometric RNA tokens through a geometric Transformer, finite scalar qua
   <img alt="RNA 3D" src="https://img.shields.io/badge/domain-RNA%203D-168B72">
 </p>
 
-[Overview](#overview) | [Checkpoints](#checkpoint-zoo) | [Quick start](#quick-start) | [API](#api-reference) | [Evaluation](#evaluation) | [Citation](#citation)
+[Paper](https://huggingface.co/papers/2603.19636) | [Code](https://github.com/Zhangz312/RiboSphere) | [Overview](#overview) | [Checkpoints](#checkpoint-zoo) | [Quick start](#quick-start) | [API](#api-reference) | [Evaluation](#evaluation) | [Citation](#citation)
 
 </div>
 
@@ -265,4 +266,4 @@ year={2026},
   
 **From continuous RNA geometry to a discrete, interpretable structural alphabet.**
 
-</div>
+</div>