[cbrnr]

This is the last part of the cleanup that started with #578, #580, #581, #582 and #588. It builds the documentation without warnings, applies one docstring style everywhere, and moves the package to a src layout. Each commit can be reviewed on its own.

1. Fix all Sphinx documentation warnings. The docs build reported 94 warnings. They are fixed, and the docs workflow now builds with -W --keep-going so they stay fixed.
   • Duplicate object descriptions: repeated automodule directives and the classes documented on both the wfdb and io pages are marked :no-index:, so each object is indexed once.
   • numpydoc_class_members_toctree = False, because the autosummary stubs it links to do not exist.
   • Too short title underlines, and reStructuredText errors in docstrings (lists, literal blocks for the EDF/MATLAB/WAV format descriptions and tables, doctest continuation lines).
   • The :no-index: option needs Sphinx 7.2, so the pinned Sphinx version of the docs group goes from 7.0.0 to 7.2.6.
2. Wrap docstrings and comments at 88 columns, the same width as the code, and enable W505 in Ruff so it stays that way. This is a mechanical change, and the commit is listed in .git-blame-ignore-revs.
3. Start docstrings on the opening quote line with a one-line summary. Summaries that were wrapped over several lines or too long for one line are shortened, and the rest of the text moves into the description below. No code changes: comparing the ASTs with docstrings removed shows no difference. A few docstrings were reworded to fit, and the descriptions of csv_to_wfdb and csv2ann (which described reading a WFDB header) now match what the functions do. Also listed in .git-blame-ignore-revs.
4. Move the package to src/wfdb. This is the default module root of uv_build, so the module-root setting is removed. The tests now always run against the installed package, and docs/conf.py adds src to sys.path. Files are moved without changes, so git blame and git log --follow keep working. The wheel and the sdist build as expected.
5. Ignore the two reformatting commits in git blame, and add a note about the docstring style to DEVELOPING.md. The hashes stay valid with a merge commit, as in Replace black and pylint with Ruff #582.
6. Add AGENTS.md and CLAUDE.md with short guidance for coding agents (commands and conventions). CLAUDE.md only points to AGENTS.md.

Checked locally: Ruff lint and format, the docs build with -W --keep-going, and the tests that work offline on Python 3.11 with the lowest dependencies and on 3.15.

@tompollard this concludes the tooling and infrastructure refresh. Any remaining changes are minor, such as fixing the ignored Ruff rules, which can be done later in follow-up PRs.

[tompollard]

Very cool, thanks for the huge clean up! One minor thing: the new summary of csv_to_wfdb says "A record and header file are written if write_dir is set", but the files are written whenever record_only is False (into the current directory if write_dir is empty).

[cbrnr]

I'll fix this tomorrow! Going to bed now!

[tompollard]

Sleep well, and thanks again! I'm going to merge and we can update as needed later.

[tompollard]

Raised issue here: #590