Docs: regenerate API reference; update README dependencies

- docs/source/*.rst regenerated with sphinx-apidoc: drop removed
  modules (meteo, stx2, focus2, observation), add the api and web
  packages and the undocumented modules (atik, mako, stl, ...)
- README: current dependencies instead of the flask/gnuplotlib/
  pyvantagepro list; how to install the Atik Python SDK wheel and
  the camera system libraries

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>