MAINT: Switching to ruff formatting

[mj-will]

As suggested in #952 (comment), we should considering switching from black+flake8 to ruff

[ColmTalbot]

I'm going to use this as a test of copilot agent mode.

Specific steps:

• update the entire project to follow ruff formatting with default settings
• update the contributing guide to describe this change
• update the pre-commit test in the CI pipeline
• ignore the commit that applied the reformatting to all files

All changes should be made in a single pull request.