Initialize the public Rethink Studios docs site:
- mkdocs.yml: Material theme, light/dark palette toggle, pymdownx
extensions, search, four-section nav skeleton.
- docs/index.md landing page with a card grid.
- Stub index pages for deploy, conventions, libraries, runbooks.
- .gitignore excludes .claude/, site/, and Python build cruft.
Deploy guide deferred; deploy section is a placeholder for now.
Signed-off-by: disqualifier <dev@disqualifier.me>