Align Sphinx docs root with GitHub Pages artifact root (no repo-root docs file required)

[Copilot]

GitHub Pages was deploying successfully but serving a 404 at the site root because the built docs entry page was nested (docs/index.html) instead of artifact-root index.html. The change keeps documentation scoped to the docs folder while ensuring Pages resolves / correctly.

• Root doc alignment

  • Updated Sphinx root doc configuration so the generated entry page is index.html at the deploy artifact root (the folder uploaded to Pages), rather than a nested docs path.

• Docs source/layout consistency

  • Kept documentation content under docs/ and adjusted docs entry wiring so docs remain organized in the docs tree without requiring a committed static index.html at repository root.

• Duplicate root prevention

  • Excluded the alternate docs index path from Sphinx input to avoid multiple competing root documents in the build graph.

# docs/conf.py
root_doc = "index"
exclude_patterns = [
    # ...
    "docs/index.md",
]