Migrate dev tooling from black/isort/pylint to ruff

[hf-krechan]

Tracking issue for migrating this repo's dev tooling off black/isort/pylint onto ruff.

Checklist:

• Merge black/isort/pylint dependency groups into a single linting group with ruff
• Translate [tool.black]/[tool.isort]/[tool.pylint]/.pylintrc config into [tool.ruff]
• Update .pre-commit-config.yaml
• Update CI workflows (linting.yml, formatting.yml)
• Run ruff, fix/triage findings
• Update README/docs mentioning black/isort/pylint
• Open PR, request Copilot review, resolve all comments

[hf-krechan]

Progress: pyproject.toml/.pylintrc/.pre-commit-config.yaml/CI translated, ruff auto-fix applied and triaged (410 findings fixed/resolved, 2 pre-existing public-field mixedCase names noqa'd rather than renamed since renaming is a breaking API change), docs updated. About to open the PR.

[hf-krechan]

Migration complete: #1120

All CI checks pass. Copilot review requested and completed — 1 comment left (dead TYPE_CHECKING block exposed by ruff's autofix), fixed and replied.