Update GH pages deployment

[awvwgk]

No description provided.

[Copilot]

Pull request overview

This PR modernizes the GitHub Pages deployment workflow by migrating from a third-party action to GitHub's native Pages deployment actions and updating action versions.

Key Changes:

• Updated GitHub Actions versions (checkout v2→v4, setup-python v1→v5)
• Split deployment into separate build and deploy jobs following GitHub's recommended pattern
• Added concurrency controls to prevent simultaneous deployments

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 11.96%. Comparing base (aa89d4b) to head (6c1814e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #106   +/-   ##
=======================================
  Coverage   11.96%   11.96%           
=======================================
  Files           5        5           
  Lines         209      209           
  Branches       95       95           
=======================================
  Hits           25       25           
  Misses        174      174           
  Partials       10       10           

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