add ruff and ruff format project

[bboynton97]

agentstack is starting to scale to the point where we might benefit from consistent formatting.

this PR implements Ruff formatting (no functional code changes) and adds a GitHub workflow pre-merge that verifies code is formatted with Ruff

To format your code:

pip install ruff
ruff format .

[bboynton97]

Open to discussion on if formatting is necessary and if this is how we want to implement it

[bboynton97]

ignore quote with

ignore = [
    "Q000",  # Single quotes found but double quotes preferred
    "Q001",  # Single quotes found but double quotes preferred (docstring)
    "Q002",  # Single quotes found but double quotes preferred (string)
    "Q003",  # Change outer quotes to avoid escaping inner quotes
]

[bboynton97]

formatted files but ignored quotes