- Adds a new engine `searx/engines/openalex.py` that integrates the OpenAlex
Works API to return scientific paper results using the `paper.html` template.
- Uses the official API (no auth required); supports OpenAlex polite pool via `mailto`.
- Adds developer docs at `docs/dev/engines/online/openalex.rst`.
OpenAlex API reference: https://docs.openalex.org/how-to-use-the-api/api-overview
