Security maintenance release.
Changes:
- Updated GitHub Actions to Node-24-compatible major versions: actions/checkout@v6, actions/setup-python@v6, github/codeql-action@v4.
- Updated Docker base image to node:26-bookworm-slim.
- Documented the security-maintenance changes in CHANGELOG.md.
Validation:
- python -m py_compile src/codex_openai_bridge.py scripts/configure_openwebui_provider.py
- python -m unittest discover -s tests
- bash -n install.sh
- local Markdown link validation
- CI and CodeQL completed successfully on main with CodeQL results_count=0