test: #3633123 Add functional tests for Varbase AI Context

Issue: https://www.drupal.org/i/3633123

Adds the Varbase functional testing suite (@vardot/varbase-e2e) and a varbase-e2e-test job: a fresh Varbase 11 site, the recipe applied twice, 12 scenarios, no AI key.

• CI needs no AI provider.

Scenarios (12):

01-01-ai-context-items.feature

• Check the "Varbase AI Editorial Rules" context item is published at global scope
• Check the "Varbase AI Safety Guardrails" context item is published at global scope
• Check the "Varbase Brand & Identity Guidelines" context item is published at global scope
• Check up to ten global context items can be sent with each AI call
• Check the global scope is enabled
• Check the webmaster can open a starter item to adapt it to the site

01-02-ai-context-access.feature

• Check the "Content editor" user can read a published context item but not change it
• Check the "Content admin" user can read a published context item but not change it
• Check the "SEO admin" user can read a published context item but not change it
• Check the "Site admin" user can read a published context item but not change it
• Check an editor cannot list or manage the context items
• Check an anonymous visitor cannot read a context item

Green locally with gitlab-ci-local: 12 passed.

AI-Generated: Yes

Checkpoints:

• File an issue
• Addition/Change/Update/Fix
• Testing to ensure no regression
• Automated unit testing coverage
• Automated functional testing coverage
• UX/UI designer responsibilities
• Readability
• Accessibility
• Performance
• Security
• Developer Documentation
• User Guide Documentation
• Reviewed by human
• Code review by maintainers
• Full testing and approval
• Credit contributors
• Review with the product owner
• Release notes snippet
• Release

🤖 Generated with Claude Code