Using a worker fixture forces a new worker. This might be unexpected
when part of the test file runs in one worker, and another runs
in another worker. Top-level use of worker fixtures is still fine.
We used to sort based on workerHash, and that changes depending on
the exact worker fixtures list. Now we replace workerHash with
an ordinal when constructing the TestGroup list to preserve the
natural order.
- Source now lives at `src/test`.
- Former folio tests live at `tests/playwright-test`.
- We use `src/test/internal.ts` that exposes base test without
Playwright fixtures for most tests (to avoid modifications for now).
- Test types live in `types/testFoo.d.ts`.
- Stable test runner is installed to `tests/config/test-runner` during `npm install`.
- All deps including test-only are now listed in `package.json`.
Non-test deps must also be listed in `build_package.js` to get included.
