Resolved conflict by keeping env var approach from main and updating
the default to include both localhost:3000 and localhost:3001.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Defaults to localhost:3000 for local dev. Server deployments can
pass a comma-separated list via the environment.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>