Test loading multiple applications on the same page

Although not a common workflow, we do support debugging multiple DDC applications on the same page. We should add a few smoke tests to `package:dwds` to ensure this workflow is properly supported.

Start by inspecting the existing smoke tests in package:dwds and identify how DDC applications are loaded and debugged on one page. Add coverage for multiple applications, then run the package's test suite to confirm the workflow is supported without regressions.

Written by the indexing model from the issue text.