Add functional tests for the ECA Workflow Modeler swap

Problem/Motivation

The Varbase Content Base recipe switched its default ECA modeler from BPMN.iO to the Workflow Modeler in #3612486 (MR !10, merged). That change has no automated test proving the swap: nothing asserts that modeler, modeler_api, eca and eca_ui are enabled, that bpmn_io is not, that the ECA "add" screen resolves to the Workflow Modeler, or that the shipped redirect_403_to_login model still opens and renders in it. A regression could silently re-introduce BPMN.iO, or break the shipped model, with nothing in the pipeline to catch it.

Steps to reproduce

Apply the Varbase Content Base recipe on a plain Drupal site, so the Workflow Modeler is the only ECA editor present, and look for an automated test that proves the swap. There is none.

Proposed resolution

Add a webship-js (Playwright + Cucumber-js) acceptance suite under tests/ that, applied on a plain Drupal site where the Workflow Modeler is the only ECA editor, asserts (isolation acceptance tests):

• modeler, modeler_api, eca and eca_ui are enabled and bpmn_io is NOT enabled;
• the ECA add screen (/admin/config/workflow/eca/add) resolves straight to the Workflow Modeler;
• the shipped redirect_403_to_login model opens and renders in the Workflow Modeler (React Flow nodes) with zero JavaScript errors, and is tagged modeler_id: workflow_modeler;
• zero configuration objects contain "bpmn".

Wire a minimal, OPT-IN GitLab CI job (kept out of the default fast pipeline; runs only when the RUN_RECIPE_BROWSER_TESTS CI/CD variable is set to 1, or via a manual pipeline run) that builds a plain Drupal site, applies the recipe, and runs the suite.

AI-Generated: Yes (Claude Code assisted with drafting this issue summary, the test suite and the opt-in CI job; a human reviews before merge).

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ❌ Testing to ensure no regression
• ✅ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Code review from 1 Varbase core team member
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ❌ Release

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• N/A