Fix ReadTheDocs conda environment configuration

- Change python>=3.11 to python=3.12 (conda requires exact version)
- Add missing pandas>=2.2 dependency
- Keep proven mambaforge-22.9 version

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

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

Author: orionarcher

docs/requirements.yaml

@@ -4,11 +4,12 @@ channels:
   - defaults
 dependencies:
     # Base depends
-  - python>=3.11
+  - python=3.12
   - pip
   - numpy>=2.2
   - pytest
   - mdanalysis>=2.8
+  - pandas>=2.2
   - nglview
   - nbsphinx
   - ipython