feat: pelican publish action

[lukzmu]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces a new GitHub Action for publishing Pelican static sites to GitHub Pages. The action automates the build process using uv and deploys the generated site.

• Added a new composite action that builds Pelican sites and deploys to GitHub Pages
• Updated documentation to include the new pelican-publish action

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
pelican-publish/action.yml	New composite action for building and deploying Pelican sites
README.md	Updated documentation to list the new pelican-publish action

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