Use best-practice pyproject.toml, and uv for managing dependencies

[normanlorrain]

Python has evolved over the years, with respect to package management. The requirements.txt file nas now been replaced by pyproject.toml. Also, pip is losing favour to the uv tool.

I'm trying to stay with best practices, so this PR makes the changes.

The docker command is the same: docker compose up app. The docker base image changed to include the uv tool.

Done with the assistance of Grok AI.
Tested on Linux Mint.

[normanlorrain]

Separate comment for discussion...
I'm not a docker expert, but I did find you can run docker compose run app bash to get to a shell prompt permitting use of the helper scripts. Perhaps there's something better @mrbiggred ?