fix: Run CI tests in serial to avoid worker termination

- Add --runInBand --maxWorkers=1 to prevent Jest worker crashes
- Fixes SIGTERM errors in GitHub Actions environment
- Tests pass but workers were being terminated after 332s

Author: michaeloboyle

.github/workflows/ci.yml

@@ -32,10 +32,10 @@ jobs:
       run: npm run build
 
     - name: Run tests
-      run: npm test
+      run: npm test -- --runInBand --maxWorkers=1
 
     - name: Check test coverage
-      run: npm run test:coverage
+      run: npm run test:coverage -- --runInBand --maxWorkers=1
 
     - name: Upload coverage to Codecov
       if: matrix.node-version == '20.x'