ruff is installed and configured but never runs in CI

[royalpinto007]

Problem

ruff is declared as a dev dependency and configured in pyproject.toml:

dev = ["pytest>=8.3", "ruff>=0.7"]

[tool.ruff]
line-length = 100

.github/workflows/ci.yml never runs it. The workflow installs .[dev], runs pytest -q, and smoke tests the CLI. No lint step. So ruff is installed on every CI run, across both matrix Python versions, and never used, and the configured line length is enforced by nothing.

Suggested approach

1. Add a lint step after the install, before the tests so failures surface fast:

   - run: ruff check .

2. Decide about formatting too: either add ruff format --check . or state in CONTRIBUTING.md that formatting is not enforced. Half-configured tooling is what created this issue in the first place.
3. Run ruff check . locally and fix whatever it reports. Please fix the findings rather than disabling the rules that produced them. If something looks like a real bug rather than style, open a separate issue for it instead of folding it into this PR.
4. Consider running lint only on the newest matrix Python version, since linting twice tells you nothing new.
5. Add the command to CONTRIBUTING.md.

Done when

• CI fails on a lint violation.
• The repository is clean under its own ruff configuration.
• CONTRIBUTING.md documents the command.

Good first issue: a few lines of YAML plus whatever cleanup ruff asks for.

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