Add a user-invocable `/lint` skill that wraps
`ruff check` with staged-file defaults and piker's
`ruff.toml` config via a PEP 723 script.
The `ruff.toml` (from prior commit) now enforces
piker's `'''` multiline docstring convention with
`D2xx` formatting rules: summary on second line
(D213), closing quotes on separate line (D209), blank
line between summary and description (D205), plus
`W` trailing-whitespace and cherry-picked `D4xx`
content checks.
Deats,
- `scripts/check.py`: pure-stdlib wrapper that
defaults to staged `.py` files via
`git diff --cached`, with `--all`, `--fix`,
`--diff`, and `--stats` flags.
- calls `ruff` from `$PATH` (works with nixpkgs,
nvim-bundled, or pip-installed).
- prints clear install guidance if `ruff` not found.
- `SKILL.md`: documents usage, common violations
(D213, D205, D204), and fix patterns for
converting to piker's docstring style.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code