Switch linting and formatting from flake8+isort+black to ruff; add typos to pre-commit; fix typos

[akx]

As it says on the tin.

I noticed ruff was installed in the dev deps, but not configured similarly in pre-commit-config.

Then I just happened to have crate-ci/typos in my pre-commit-config template, so in it went too.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (9929991) to head (2bf2118).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #281   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines          130       130           
  Branches        14        14           
=========================================
  Hits           130       130           

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