fix: Apply the default recipe only when the module is installed on its own

Problem/Motivation

webai_install() applies the Web AI default recipe every time the module is installed. The other web* modules guard that call: they skip it during a configuration import, and when the default recipe itself installs the module, because the recipe is already being applied.

Web AI is one of the two modules still missing that guard.

Proposed resolution

Give webai_install() the same shape as webpage_install(): take $is_syncing, return during a configuration import, and apply the default recipe only when the module is installed on its own.

Remaining tasks

• ✅ File an issue about this project
• ❌ Fix to this project
• ❌ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ❌ Code review by maintainers

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