PER-10670: Switch to vitest

[liam-lloyd]

Jest doesn't officially support ESM. We'd like to move this repo to ESM,
as that appears to be the way of the future (and we have some
dependencies that in their latest releases only offer ESM support). To
that end, this commit replaces Jest with Vitest.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.86%. Comparing base (fdbdc9a) to head (03b784a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #789      +/-   ##
==========================================
- Coverage   98.56%   97.86%   -0.70%     
==========================================
  Files         109      124      +15     
  Lines        2783     5583    +2800     
  Branches      462     1059     +597     
==========================================
+ Hits         2743     5464    +2721     
- Misses         36      117      +81     
+ Partials        4        2       -2     

Flag	Coverage Δ
api	97.86% <ø> (-0.70%)	⬇️

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[liam-lloyd]

The codecov difference here seems to come from differences in how jest and vitest count coverage, not from any actual reduction in coverage.

[cecilia-donnelly]

This looks straightforward and the tests are passing. I have a question about the import setup inline.

[cecilia-donnelly]

It looks like we imported these from jest in some central location and have to import them in each file from vitest -- is that expected?

[liam-lloyd]

Yes, this is a difference in philosophy between jest and vitest. Jest imported a bunch of stuff automatically, vitest wants you to be explicit

[cecilia-donnelly]

Some Claude review comments:

- packages/event_utils lost its jest.config.js with no vitest.config.ts replacement — dormant since it has no tests yet, but will break  path-alias resolution the moment one is added.
- AGENTS.md still tells contributors to use jest-when, which was removed from package.json in favor of vitest-when.
-  a duplicated hand-rolled @stela/logger mock in trigger_archivematica instead of the new shared mock, vitest-mock-extended added  separately in 6 package.json files instead of hoisted at root, coverage.clean: false risking stale coverage output, and the old silent:   true Jest option having no Vitest equivalent (noisier CI logs).

[liam-lloyd]

Some Claude review comments:

- packages/event_utils lost its jest.config.js with no vitest.config.ts replacement — dormant since it has no tests yet, but will break  path-alias resolution the moment one is added.
- AGENTS.md still tells contributors to use jest-when, which was removed from package.json in favor of vitest-when.
-  a duplicated hand-rolled @stela/logger mock in trigger_archivematica instead of the new shared mock, vitest-mock-extended added  separately in 6 package.json files instead of hoisted at root, coverage.clean: false risking stale coverage output, and the old silent:   true Jest option having no Vitest equivalent (noisier CI logs).

I think it's correct for event_utils to not have a vitest config if it doesn't have tests. I've fixed the other things noted here (except the last one, which doesn't have a fix)