Deploy documentation to GitHub Pages

[parthdongre]

Summary

Publish the existing MkDocs documentation as a real documentation site instead of only validating it in CI.

Why

FrameVitals already has mkdocs.yml, a docs/ tree, and a strict docs build workflow, but the public package metadata still points users back to the repository docs folder. A deployed docs site would make the project easier to discover, navigate, and trust.

Scope

• Add a GitHub Pages deployment path for the MkDocs site.
• Keep mkdocs build --strict as a required validation step.
• Deploy only from the stable branch/release flow.
• Update package metadata and README documentation links to the deployed site.
• Document how maintainers preview docs locally.

Acceptance criteria

• Documentation is publicly reachable through GitHub Pages.
• Broken links or strict MkDocs warnings fail CI before deployment.
• pyproject.toml uses the deployed site for the Documentation URL.
• README links users to the deployed docs site.
• Deployment is reproducible from repository configuration only.

Priority: P0 — project maturity
Suggested labels: documentation, infrastructure