Add Sphinx documentation with pull request preview deployments

[mikelangmayr]

• Add a Sphinx site under docs/, Markdown via MyST, furo theme, covering camerad core, the instruments, the emulator and the Python bindings
• Python API page is autodoc against the compiled camera_interface module, so it cannot drift from the pybind11 bindings
• C++ reference is narrative and links to source, since Doxygen coverage is too thin for a generated reference to read well
• Add .github/workflows/docs.yml: builds with -W on every PR and on merge to main, publishes PRs to previews/pr-<N>/ on gh-pages with a commented link, publishes main to the site root, and uploads the HTML as an artifact for fork PRs
• Remove the stale Jekyll _config.yml, which described a Pages setup that was never enabled
• README gains a link to the site and keeps its build and run content

This is the first milestone: scaffold, toolchain and preview plumbing, with real but not yet complete content. Pages needs enabling on the repo with source gh-pages before preview links resolve.

Verified with a clean local sphinx-build -W and by checking the rendered output for the conditional Python API fallback, the landing page cards and source links.

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-09-23 20:19 UTC

[scizen9]

Good!