chore(ruff): converge on the standard's ruff block

[lesnik512]

Summary

Converges [tool.ruff] on the block in the modern-python standard. Configuration only; no behaviour change in the package.

Changes

• fix = true, and target-version removed: ruff derives it from requires-python.
• The ignore list is the standard's eight entries, each with its one-line reason. Ignores measured to suppress nothing across the org are gone (G004, TRY003, EM102 where present). Repo-specific ignores the standard allows are kept, with a reason.
• S101 moves from a global ignore to "tests/**": assert is the test idiom, and in library code it is a finding. There were no package-side hits to fix.

Checklist

• Lint and format pass (just lint-ci)
• Type check passes (ty, part of lint-ci)
• Tests pass and new behavior is covered — no behaviour change; CI runs the suite
• Build succeeds — no packaging change
• Repo metadata stays consistent across the three surfaces — untouched