migrate Jest to Vitest

[irahopkinson]

• fix build/lint config
• also align Node 24 types

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.40%. Comparing base (42ab65c) to head (c84648b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #45      +/-   ##
==========================================
- Coverage   86.30%   81.40%   -4.90%     
==========================================
  Files           4        4              
  Lines         365      328      -37     
  Branches      111       78      -33     
==========================================
- Hits          315      267      -48     
+ Misses         50       39      -11     
- Partials        0       22      +22     

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