fix(logging): Add NullHandler to sphinx_autodoc_pytest_fixtures

why: CLAUDE.md requires NullHandler in library __init__.py files to
suppress spurious stderr output when no handler is configured.
what:
- Add logging import and NullHandler after all imports

Author: tony

packages/sphinx-autodoc-pytest-fixtures/src/sphinx_autodoc_pytest_fixtures/__init__.py

@@ -13,6 +13,7 @@
 
 from __future__ import annotations
 
+import logging
 import typing as t
 
 from docutils import nodes
@@ -82,6 +83,8 @@
 if t.TYPE_CHECKING:
     from sphinx.application import Sphinx
 
+logging.getLogger(__name__).addHandler(logging.NullHandler())
+
 
 def setup(app: Sphinx) -> SetupDict:
     """Register the ``sphinx_autodoc_pytest_fixtures`` extension.