🔥 docs: remove paper button from homepage index.html

Remove the '📄 论文' (Paper) button linking to Zenodo DOI from the
docs homepage. Paper is currently not ready for public display.

Author: ouyangyipeng

docs/index.html

@@ -276,7 +276,6 @@ <h1>The First<br><span class="gradient-text">Harness Native</span><br>Agent Lang
 
     <div class="hero-links">
       <a href="https://www.nexa-lang.com" target="_blank" rel="noopener">🌐 nexa-lang.com</a>
-      <a href="https://doi.org/10.5281/zenodo.19994263" target="_blank" rel="noopener">📄 论文</a>
       <a href="https://github.com/Nexa-Language/Nexa" target="_blank" rel="noopener">⭐ GitHub</a>
     </div>