Use Vitest v1.0.0-beta.4, run browser tests in CI

Per commit af2084b, running headless
browser tests at this moment requires at least Vitest v1.0.0-beta.3.
Updating to the beta version seems fine to me so far.

I found a way to run the headless browser tests in CI without making a
mess of the package.json script by using alternative config files.

Updated vite.config.js to use defineConfig() to make type information
available in IntelliJ. Added the buildDir() function to vite.config.js
to help configure test.outputFile in vitest.config.ci-browser.js.

---

I played around with trying to collect coverage from running the tests
in the browser. I'll try to add it in a future commit, but the basic
issues are:

- @vitest/coverage-istanbul is required, because @vitest/coverage-v8
  doesn't work in the browser.

- The command to run coverage is then:
  pnpm test -- --browser --coverage.enabled --coverage.provider=istanbul

- It currently reports 0% coverage, because when the tests call
  window.open() (via PageLoader.load()), the modules are loaded in a
  separate process.

I confirmed this last point using a temporary test that imported the
main.js module directly after creating a <div id="app"> on
window.document, generating 100% coverage. Running the test using
Node.js and JSDOM doesn't have the same problem, because JSDOM doesn't
open a new process.

I've ideas on how to handle this and generate coverage from the
browser-run tests in an elegant way that I'll try soon. I'm not sure
that I'll absolutely enable this in CI, but we'll see after I try out
these ideas and think about it some more.

strcalc/build.gradle.kts

@@ -158,7 +158,7 @@ val mergeTestReports = fun(resultsDir: File) {
 
     // The `pnpm_test-ci` output is already merged. Trying to merge it again
     // results in an empty file, so skip it.
-    if (taskName == "test-frontend") return
+    if (taskName.startsWith("test-frontend")) return
 
     val relResultsDir = relativeToRootDir(resultsDir.toPath())
     val reportTaskName = "merged-report-$taskName"

strcalc/src/main/frontend/package.json

@@ -11,19 +11,19 @@
     "test": "vitest",
     "test-run": "vitest run",
     "test-ui": "vitest --ui --coverage",
-    "test-ci": "vitest run --coverage --reporter=junit --reporter=default",
+    "test-ci": "vitest run --config vitest.config.ci-jsdom.js && vitest run --config vitest.config.ci-browser.js",
     "coverage": "vitest run --coverage"
   },
   "devDependencies": {
     "@stylistic/eslint-plugin-js": "^1.2.0",
-    "@vitest/browser": "^0.34.6",
-    "@vitest/coverage-v8": "^0.34.6",
-    "@vitest/ui": "^0.34.6",
+    "@vitest/browser": "1.0.0-beta.4",
+    "@vitest/coverage-v8": "1.0.0-beta.4",
+    "@vitest/ui": "1.0.0-beta.4",
     "eslint": "^8.53.0",
     "eslint-plugin-vitest": "^0.3.9",
     "jsdom": "^22.1.0",
     "vite": "^4.5.0",
-    "vitest": "^0.34.6",
+    "vitest": "1.0.0-beta.4",
     "webdriverio": "^8.23.0"
   }
 }