API docs parity: Python

## Python API Docs

**Parent epic:** #1653

**Doc format:** Docstrings (reStructuredText or Google/NumPy style) processed by [Sphinx](https://www.sphinx-doc.org/) or [pdoc](https://pdoc.dev/). Type hints in source also serve as documentation.

**Culture:** Strong convention to write docstrings. PyPI does **not** require a docs build to publish, but the community expects it. `help()` in the REPL reads docstrings directly.

**Hosting analogues:**

| Service | How it works |
|---------|-------------|
| [Read the Docs](https://readthedocs.org/) | De facto standard host — builds Sphinx/MkDocs on push; free for OSS. Closest cultural equivalent to javadoc.io |
| [pdoc](https://pdoc.dev/) | Zero-config generator from docstrings |
| PyPI project page | Renders the long description (usually README), not full API docs |

**Key difference from Java:** No bundled doc artifact in the wheel/sdist. Docs are a separate CI deliverable, typically hosted on Read the Docs.