Add custom thumbnails to static directory with sphinx_gallery_thumbnail_path

- Added custom animated GIF and static PNG thumbnails to docs/_static/thumbnails/
- Updated 9 example scripts to reference custom thumbnails using sphinx_gallery_thumbnail_path
- Thumbnails will now be included in Read the Docs builds and version control
- Animated examples: chemtrails, animate_MDS, animate_spin, animate, precog, save_movie
- Static examples: explore, save_image, analyze

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

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

Author: jeremymanning

docs/_static/thumbnails/sphx_glr_analyze_thumb.png

@@ -13,6 +13,8 @@
 visualized.
 """
 
+# sphinx_gallery_thumbnail_path = '_static/thumbnails/sphx_glr_analyze_thumb.png'
+
 # Code source: Andrew Heusser
 # License: MIT