feat: #3610873 Grant event content and taxonomy permissions to the Varbase roles

The recipe created the Event content type but granted no permissions, so on a fresh site no role could create, edit or delete an event without the site builder adding permissions by hand.

This adds user.role.* grantPermissions actions to the recipe:

• Content editor and Content admin get create / edit / delete of event content and manage the Event categories terms.
• SEO admin and Site admin get their content-management sets.
• Content admin and Site admin also get the access_unpublished permissions for events, Event categories and the shared Tags vocabulary, so the unpublished-preview links are limited to the admin roles. Anonymous and authenticated get no event permissions.

Verified on a fresh install: a Content editor can add, edit and delete an event through the UI; anonymous has no access_unpublished on events while Content admin and Site admin do. Installs with 0 errors on Varbase Starter and on the Educare site template.

Issue: https://www.drupal.org/project/varbase_events_base/issues/3610873

This change was made with the assistance of an AI, as disclosed under the Drupal AI policy.

Checkpoints

• 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
• Reviewed by a human
• Code review by maintainers
• Full testing and approval
• Credit contributors
• Review with the product owner
• Update Release Notes
• Release