fix: Increase Node heap size to 6GB for CI tests

- Set NODE_OPTIONS --max_old_space_size=6144 (6GB)
- GitHub Actions runners have 7GB RAM available
- Should prevent OOM errors during 10-minute serial test run
- All 294 tests pass, just need more heap space

Author: michaeloboyle

.github/workflows/ci.yml

@@ -33,6 +33,8 @@ jobs:
 
     - name: Run tests with coverage
       run: npm run test:coverage -- --maxWorkers=1
+      env:
+        NODE_OPTIONS: --max_old_space_size=6144
 
     - name: Upload coverage to Codecov
       if: matrix.node-version == '20.x'