fix: Force serial test execution in CI to prevent OOM

- Use --maxWorkers=1 in CI to run tests serially
- Prevents 'heap out of memory' errors in limited CI environment
- Local development still uses Jest config maxWorkers: '50%'
- Trade-off: CI slower but stable vs parallel but OOM

Author: michaeloboyle

.github/workflows/ci.yml

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