Migrate to UV for development

[senthurayyappan]

Poetry has been great so far, but there are still some pain points:

1. Build times are awfully long at times
2. Resolving dependencies also takes a while
3. Poetry now doesn't support the 'poetry shell' command anymore

UV is a nicer alternative to poetry and works well with our current ruff setup for checks.

It would also be better to switch to ty from mypy.