Add custom gallery thumbnail configuration for animated examples

- Configure sphinx-gallery to use custom thumbnails for animations
- Add thumbnail override configuration for 6 animated examples
- Enable proper thumbnail generation for interactive and special examples

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

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

Author: jeremymanning

docs/conf.py

@@ -239,4 +239,16 @@
         'scipy': 'https://docs.scipy.org/doc/scipy/reference/',
         'pandas': 'https://pandas.pydata.org/pandas-docs/stable/',
         'scikit-learn': 'https://scikit-learn.org/stable/',
-    }}
+    },
+    # Use custom thumbnails for animated examples
+    'thumbnail_number': -1,  # Use last generated image as thumbnail
+    'image_scrapers': ('matplotlib',),
+    # Override thumbnails with custom GIFs for animated examples
+    'thumbnails': {
+        '../examples/chemtrails.py': 'images/thumb/sphx_glr_chemtrails_thumb.gif',
+        '../examples/animate_MDS.py': 'images/thumb/sphx_glr_animate_MDS_thumb.gif',
+        '../examples/animate_spin.py': 'images/thumb/sphx_glr_animate_spin_thumb.gif',
+        '../examples/animate.py': 'images/thumb/sphx_glr_animate_thumb.gif',
+        '../examples/precog.py': 'images/thumb/sphx_glr_precog_thumb.gif',
+        '../examples/save_movie.py': 'images/thumb/sphx_glr_save_movie_thumb.gif',
+    }