Sphinx build fails on .codespell/test_data/test_notebook.ipynb

[drbenvincent]

Summary

The .codespell/test_data/test_notebook.ipynb file inside docs/source/ is picked up by Sphinx during documentation builds, causing a build failure:

sphinx.errors.ThemeError: An error happened in rendering the page .codespell/test_data/test_notebook.
Reason: NotADirectoryError(20, 'Not a directory')

Steps to reproduce

1. Clean the docs build cache: make cleandocs
2. Build the docs: make html
3. The build fails with the error above.

The issue may not always surface if there is a stale docs/_build cache, but it reliably reproduces on a clean build.

Root cause

The .codespell/test_data/ directory (added in commit 54ff563) lives inside docs/source/, which is the Sphinx source root. Sphinx discovers all .ipynb files under this directory via the myst-nb parser, including test fixtures that are not intended to be documentation pages.

The current exclude_patterns in docs/source/conf.py only excludes _build, Thumbs.db, and .DS_Store — it does not exclude .codespell.

Proposed fix

Add .codespell to the exclude_patterns list in docs/source/conf.py:

exclude_patterns = ["_build", "Thumbs.db", ".DS_Store", ".codespell"]

Alternatively, the .codespell/test_data/ directory could be moved outside of docs/source/ entirely (e.g. to tests/codespell/), but the exclude pattern is the minimal fix.