Add the Web AI default recipe to the site template

Problem/Motivation

The site template ships no AI. A site that wants AI has to pick the AI modules and providers, install them and choose a default provider by hand.

Steps to reproduce

1. Install the site template.
2. Look for the AI module and a provider: nothing is installed.

Proposed resolution

• Require drupal/webai, like the other Webship modules.
• List modules/contrib/webai/recipes/default in the recipes of the template. A recipe installs modules with config entity installation disabled, so the install hook of the Web AI module cannot apply its own recipe.

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
• ❌ Code review by maintainers

User interface changes

The AI settings and provider settings pages are available after the install.

API changes

None.

Data model changes

None.

AI-Generated: Yes