[max-models]

Replaces the Sphinx docs with the shared Astro + Starlight setup (@max-models/starlight-theme v0.4.0), like the other max-models sites.

• New home, installation and quickstart pages (from the README); docs/matplotlib-import-support.md is now a guide in the nav
• The 17 tutorial notebooks are executed and converted by starlight-notebooks; old tutorials/tutorial_XX.html URLs redirect
• An API reference from starlight-pydocs (the Sphinx site had none)
• The docs workflow is the theme's reusable one, with the same TeX Live packages; tikzfigure comes from PyPI
• Removed docs/source/, the Sphinx Makefile/make.bat and the Sphinx packages of the docs extra; new docs-* Makefile targets
• .gitignore: the *.json rule no longer hides docs/package.json and friends

Known: tutorial 08's Plotly figures are not shown yet (the notebook converter skips Plotly outputs), and tutorial 14 cell 9 raises ValueError: Axis limits cannot be NaN or Inf while drawing.