chore(deps): update pre-commit hooks (#6126)

* chore(deps): update pre-commit hooks

updates:
- [github.com/pre-commit/mirrors-clang-format: v22.1.5 → v22.1.8](https://github.com/pre-commit/mirrors-clang-format/compare/v22.1.5...v22.1.8)
- [github.com/astral-sh/ruff-pre-commit: v0.15.20 → v0.16.1](https://github.com/astral-sh/ruff-pre-commit/compare/v0.15.20...v0.16.1)
- [github.com/pre-commit/mirrors-mypy: v2.1.0 → v2.3.0](https://github.com/pre-commit/mirrors-mypy/compare/v2.1.0...v2.3.0)
- [github.com/codespell-project/codespell: v2.4.2 → v2.4.3](https://github.com/codespell-project/codespell/compare/v2.4.2...v2.4.3)

* style: pre-commit fixes

* fix: adapt to the ruff 0.16 default rule set

The hook update pulled in ruff 0.16, which expanded its default rules and
autofixed `self: S -> S` to `-> Self`. That fix added a runtime
`typing_extensions` import to setup_helpers.py, which must stay
dependency-free; it broke every test job whose environment does not supply
that package. The import is now guarded by TYPE_CHECKING.

Also replace the `exec` in docs/conf.py with an importlib module load,
parenthesize implicit string concatenations in list literals, mark unused
unpacked variables with a leading underscore, and make noxfile.py
executable to match its shebang.

The remaining new rules are silenced per-file, with reasons: the chrono
tests check naive local time on purpose, and the other rules conflict with
how the tests are written.

Assisted-by: ClaudeCode:claude-opus-5

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Henry Schreiner <henryfs@princeton.edu>