Fix pkgdown workflow by installing the local package before site build

[Copilot]

The pkgdown GitHub Actions job was failing during site generation because pkgdown::deploy_to_branch() attempted to load fakir for reference/example building before the package had been installed. This change updates the workflow so the local package is available during the pkgdown build.

• Workflow fix

  • Update the pkgdown dependency setup step to install the repository package in addition to pkgdown.
  • Keep the existing template install and deploy flow unchanged.

• Effect on pkgdown build

  • Ensures fakir can be loaded when pkgdown builds reference pages and evaluates examples.
  • Aligns the workflow with the expected r-lib/actions pkgdown pattern for site generation from source.

• Change

  - uses: r-lib/actions/setup-r-dependencies@v2
    with:
      extra-packages: pkgdown, local::.
      needs: website