Honor FAQ and library resource switches

[oiahoon]

Summary

• honor the existing FAQ and Library resource switches during panel registration
• keep each addon independent when the other is disabled
• cover default and disabled registration with focused Pest tests

Verification

• composer test:pest
• vendor/bin/pint --test
• vendor/bin/phpstan analyse src/SkyPlugin.php --no-progress --debug --memory-limit=1G
• git diff --check

Fixes #269