Vitest 5 (#3368)

https://vitest.dev/blog/vitest-5.html
https://vitest.dev/guide/migration/

Two changes needed:

- Switch the date-picker’s partial text assertion to
`toMatchTextContent`. `toHaveTextContent` now requires exact text, and
the button includes the icon’s “Select” title.
- Ignore `.vitest/` and include it in CI artifacts. Automatic failure
screenshots now go there instead of following our existing
`screenshotDirectory` setting.

The promised perf improvements turned out to be pretty small:

| Suite | 4.1.11 | 5.0.0, upgrade only | Change |
|---|---:|---:|---:|
| Node | 1.39s | 1.33s | −4.1% |
| Chromium | 4.15s | 4.15s | Unchanged |
| Node + all three browsers | 9.13s | 8.61s | −5.6% |

Second commit enables
[`fsModuleCache`](https://vitest.dev/config/fsmodulecache), as
recommended by `vitest doctor`. Warm Node runs drop to **1.09s**, about
22% faster than v4. This mainly helps local test runs.

Author: david-crespo

.github/workflows/lintBuildTest.yml

@@ -100,5 +100,7 @@ jobs:
         if: always()
         with:
           name: test-results-${{ matrix.playwright }}
-          path: test-results/
+          path: |
+            test-results/
+            .vitest/
           retention-days: 7

.gitignore

@@ -32,6 +32,7 @@ test-results/
 ci-e2e-traces/
 playwright-report/
 .e2e-logs/
+.vitest/
 .vercel
 
 # Visual regression snapshots

app/components/form/fields/DateTimeRangePicker.browser.spec.tsx

@@ -56,7 +56,7 @@ test.each([
   await expect.element(screen.getByText(`Preset: ${preset}`)).toBeVisible()
   await expect
     .element(screen.getByRole('button', { name: 'Choose a time range preset' }))
-    .toHaveTextContent(option)
+    .toMatchTextContent(option)
 })
 
 test('chooses a preset with the keyboard', async () => {