Run the private browser checks with one worker (#66)

Four private runs lost the runner during the Chromium/WebKit step: the
log stops about a minute in, cleanup cannot start, and Docker-Builder1
stays offline until restarted. Halving the browser load tests whether
the host is running out of memory; the step has room in the 40-minute
limit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/private-checks.yml

@@ -45,8 +45,9 @@ jobs:
       - name: Unit and playthrough tests with the ROM
         run: npm test -- --maxWorkers=2
       - run: npx playwright install --with-deps chromium webkit
+      # One worker: with two, the runner host dropped off mid-run (runs 122, 130, 132, 134).
       - name: Chromium and WebKit gameplay and reference comparisons
-        run: npm run test:e2e -- --workers=2 --trace=off
+        run: npm run test:e2e -- --workers=1 --trace=off
       - name: Remove private data and browser output
         if: always()
         run: rm -rf .reference test-results playwright-report test-saves