Build and deploy docs on release

[wmwolf]

Problem

The Sphinx docs under docs/ are not regenerated automatically — there's no docs workflow, and GitHub Pages just serves the committed HTML. That HTML is a static 2017 snapshot (last built in d11dd4c), so the published docs are missing years of features (.mod model reading, the file_type param, pickle support, etc.). They don't reflect current docstrings.

Fix

Add a docs workflow that rebuilds the docs from docstrings (sphinx.ext.autodoc) and deploys to GitHub Pages on release publication — the same trigger as the existing PyPI publish workflow — so the docs track each released version rather than churning on every push. Manual workflow_dispatch is also supported for an on-demand rebuild.

• requirements-docs.txt pins the doc toolchain (sphinx, sphinx_rtd_theme, sphinx-copybutton).
• The build command (sphinx-build -b html docs_source _site) was verified locally — builds cleanly and reflects current docstrings.

⚠️ Required one-time setup

This uses actions/deploy-pages, so the repo's Pages source must be switched from "Deploy from a branch" (/docs) to "GitHub Actions" under Settings → Pages. Until that's flipped, the deploy job will fail. (I can do this via gh api if you'd like — just say so.)

Follow-ups (not in this PR)

• Once Pages deploys from Actions, the committed docs/ HTML becomes vestigial and could be removed from the repo.
• The version/release in docs_source/conf.py (3.5.0) is stale vs setup.py (0.3.5) and could be wired to the package version.

🤖 Generated with Claude Code