Operational Cleanup

[Mr0grog]

Since I've been doing a bunch of stuff and n this repo this week, there are a few updates I'd like to make to the overall setup:

• Use uv and pyproject.toml. Should make basic setup much easier for anyone else who needs to hack on this.
• Update to latest Python.
• Set up Dependabot (it supports uv now!).
• Take stab at updating docs and closing Clarify upload_zoom_scripts steps for getting set up to run script in README #7.

[Mr0grog]

Ugh, having a lockfile from uv would be a real lifesaver here, too. It looks like the upload script started failing yesterday afternoon because Google published a buggy release of python-api-core (v2.28.0). They released a fix in v2.28.1 a few hours ago and things are working again, but with a lockfile, this never would have broken for us.

(We can also generate a kind of lockfile with pip, but uv is just a much better all-around solution these days.)