ci(guard): fail unit-tests job if [birpc] rpc is closed appears in coverage run

Captures npm run test:coverage output with tee and adds an always-run step
that greps for the teardown-race fingerprint. Any future regression where a
vi.mock factory races with birpc teardown will now surface as an explicit CI
failure rather than a silent exit-1 after all tests report green (#535).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -43,11 +43,20 @@ jobs:
           TZ: Europe/Berlin
 
       - name: Run coverage (server + client)
-        run: npm run test:coverage
+        run: npm run test:coverage 2>&1 | tee /tmp/coverage-test.log; exit ${PIPESTATUS[0]}
         working-directory: frontend
         env:
           TZ: Europe/Berlin
 
+      - name: Assert no birpc teardown race in coverage run
+        if: always()
+        run: |
+          if grep -q "rpc is closed" /tmp/coverage-test.log 2>/dev/null; then
+            echo "FAIL: [birpc] rpc is closed teardown race detected in coverage run"
+            grep "rpc is closed" /tmp/coverage-test.log
+            exit 1
+          fi
+
       - name: Upload coverage reports
         if: always()
         uses: actions/upload-artifact@v4