Fix docs version switcher missing on gh-pages branch documentation (#140)

* Initial plan

* Fix version switcher missing on gh-pages branch docs

Add switcher.json copy to branch documentation deployment to ensure
version switcher is available on all documentation pages, not just
the default branch deployment.

Co-authored-by: K20shores <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: K20shores <[email protected]>

Author: Copilot

.github/workflows/gh-pages.yml

@@ -88,6 +88,8 @@ jobs:
           id=$(docker create tuvx)
           docker cp $id:/build/docs/sphinx tmpdocs
           docker rm -v $id
+          # Copy switcher.json to enable version switcher on branch docs
+          cp docs/switcher.json tmpdocs/
           brname="${{github.ref}}"
           brname="${brname##refs/heads/}"
           brdir=${brname//\//--}   # replace '/' with '--'