Fix 404 error in Sphinx documentation navigation

- Remove problematic header_links configuration that was generating broken links
- Simplify theme options to use default navigation behavior
- Addresses user-reported 404 error for "Documentation" link in header

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremymanning

docs/source/conf.py

@@ -47,8 +47,7 @@
 html_theme_options = {
     "project_name": "Clustrix",
     "github_url": "https://github.com/ContextLab/clustrix",
-    "header_links": "Documentation|API Reference|Tutorials",
-    "footer_links": "GitHub|PyPI|Documentation",
+    "footer_links": "GitHub|PyPI",
 }
 
 html_title = "Clustrix Documentation"