Revisit declaring uv as a dev dep #1016

I think it can get confusing if care isn't taken, since e.g. it now requires activating venvs.

Pertinent to #1015 since if we don't declare it then the uv-pre-commit config needs some way to be synced.

Also consider setting a min uv version declaration explicitly to align with the uv dep... but then we need to sync those!