Treat Ruff ignore comments as pragmas

[Baltsat]

Summary

• recognize canonical # ruff:ignore[...] comments as Black pragmas
• preserve original physical lines for Ruff ignores, matching type: ignore
• add direct and end-to-end regressions for ruff:ignore should be processed as a pragma in contains_pragma_comment #5260

Fixes #5260, closes #5266

Testing

• pytest tests/test_trans.py tests/test_format.py -k ruff
• pre-commit run -a
• env -u NO_COLOR tox -e py — 476 passed, 1 skipped; 73 Jupyter tests passed

AI-assisted contribution

AI assistance was used for investigation, implementation, testing, and review. I reviewed the final diff and verified all reported commands locally.

Checklist

• The change includes regression coverage.
• Add the PR-numbered entry to CHANGES.md.

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[github-actions]

diff-shades results comparing this PR (a04af92) to main (db2e3e7):

--preview style (View full diff):

╭───────────────────────── Summary ──────────────────────────╮
│ 2 projects & 134 files changed / 1435 changes [+346/-1089] │
│                                                            │
│ ... out of 2 999 312 lines, 13 999 files & 22 projects     │
╰────────────────────────────────────────────────────────────╯
Differences found.

--stable style (View full diff):

╭───────────────────────── Summary ──────────────────────────╮
│ 2 projects & 134 files changed / 1423 changes [+343/-1080] │
│                                                            │
│ ... out of 2 999 312 lines, 13 999 files & 22 projects     │
╰────────────────────────────────────────────────────────────╯
Differences found.

---

What is this? | Workflow run | diff-shades documentation

[Baltsat]

The current corpus run shows that the unconditional implementation changes stable output in 134 files. The issue spans two formatter paths: line-preservation via is_type_ignore_comment and string-transform protection via contains_pragma_comment. I can rework both behind a single --preview feature, requiring zero stable diff-shades while retaining focused stable/preview regressions. Is that the preferred scope? I have marked the PR draft while this is clarified.