Oxygen add-on for XSpec v3.4.1

[galtm]

This pull request brings the Oxygen add-on up to date with xspec/xspec#2217.

To do, in this order:

• Merge build(oxygen): add-on v3.4.1 xspec#2217 into master. That will create the v3.4.1.zip file.
• On the branch for this PR, run hugo locally and test installation of the add-on with local URL: http://localhost:1313/editors/oxygen/oxygen-addon.xml (To check that opening xspec.xpr in your own clone disables the add-on and enables its own framework, you have to sync your clone to master.)
• Merge this PR onto hugo branch.
• Uninstall add-on, and test re-installation with remote URL: https://xspec.io/editors/oxygen/oxygen-addon.xml

Cc: @cmarchand

[galtm]

I installed and tested the add-on with Oxygen XML Editor 28.0 build 2025112606. At first, the installation option was grayed out in Oxygen XML Author 28.0 build 2025112606 as if it was incompatible. I tried again a short while later, intending to take a screen capture, and at that point the option was no longer grayed out.

The Run XSpec Test transformation scenario isn't yet compatible with tests for Schematron via XQS, but it worked with tests for XSLT, XQuery, and Schematron via SchXslt. The other transformation scenarios worked as expected. For the two XProc transformation scenarios, the bottom pane of messages indicated XML Calabash 3.x instead of XML Calabash 1.x.