Switch to pyproject.toml

App service now supports pyproject.toml and uv, we should consider replacing reqs.txt with pyproject.toml and adding a uv.lock too. [See more](https://techcommunity.microsoft.com/blog/appsonazureblog/what%E2%80%99s-new-for-python-on-app-service-for-linux-pyproject-toml-uv-and-more/4468903)

happy to open a PR for this.

Start by inspecting reqs.txt and the repository's existing project configuration. Compare the declared dependencies with the pyproject.toml and uv.lock approach described in the issue; the work is done when the project uses those files consistently and the application setup remains reproducible.

Written by the indexing model from the issue text.