Integration documentation checks

The harness runs published Phoenix integration examples against a local Phoenix server and verifies the result in Phoenix. The enabled set is deliberately incremental: scripts/testing/integration_docs/integrations.json lists the documents CI executes. INTEGRATION_CHECKS.md is only an onboarding inventory.

Run checks locally

Start Phoenix at http://127.0.0.1:6006, set the credentials required by the selected integration, then run:

make test-integration-docs

Run a single configured document with: