Mergeback v4.31.8 refs/heads/releases/v4 into main

[github-actions]

This PR bumps the version number and updates the changelog after the v4.31.8 release.

Please do the following:

• Remove and re-add the "Rebuild" label to the PR to trigger just this workflow.
• Wait for the "Rebuild" workflow to push a commit updating the distribution files.
• Mark the PR as ready for review to trigger the full set of PR checks.
• Approve and merge the PR. When merging the PR, make sure "Create a merge commit" is
  selected rather than "Squash and merge" or "Rebase and merge".

[github-actions]

Pushed a commit to rebuild the Action. Please mark the PR as ready for review to trigger PR checks.

[Copilot]

Pull request overview

This PR performs a standard mergeback after the v4.31.8 release, bumping the version to 4.31.9 and updating the changelog with the release information.

Key Changes:

• Version bumped from 4.31.8 to 4.31.9 in package.json and related files
• CHANGELOG.md updated with the 4.31.8 release entry dated 11 Dec 2025
• UNRELEASED section updated with placeholder text

Reviewed changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated no comments.

File	Description
package.json	Version bumped to 4.31.9 for next development cycle
package-lock.json	Lockfile updated to match package.json version
CHANGELOG.md	Added 4.31.8 release entry and reset UNRELEASED section
lib/*.js	Generated JavaScript files updated with new version (auto-generated, not reviewed per guidelines)

No issues were identified in this mergeback PR. The version increment and changelog updates are appropriate and follow the standard release process.