Add Varbase AI Base recipe to Varbase Starter

Problem/Motivation

The Varbase AI recipes were recently updated to 2.0.x to align with the Drupal CMS AI ecosystem and the drupal/drupal_cms_ai package.

These updates simplified the recipes so they mainly provide the required permissions
and integrations for Varbase roles when AI features are available.

#3579322: Start 2.0.x branch for Varbase AI Image Alt recipe to align with the Drupal CMS AI ecosystem and manage permissions for generating AI image alt text
#3579326: Start 2.0.x branch for Varbase AI Editor Assistant recipe to align with the Drupal CMS AI ecosystem
#3579329: Start 2.0.x branch for Varbase AI Taxonomy Tagging recipe to align with the Drupal CMS AI ecosystem

Proposed resolution

Add the Varbase AI Base recipe to Varbase Starter so AI-related functionality and permissions are prepared during installation.

• Align Varbase with the Drupal CMS AI ecosystem.
• Support the updated 2.0.x Varbase AI recipes.
• Ensure Varbase roles receive the required AI permissions.

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 varbase-11.0.0-alpha1, varbase_starter-1.0.0-alpha1

User interface changes

• N/A

API changes

• feat: #3579368 Add Varbase AI Base recipe to Varbase Starter

Data model changes

• N/A

Release notes snippet

• N/A