Permissions & module gating

• Shoppers use Compare with or without an account.
• Switching it on or off needs access to Settings → Modules.
• Editing features needs a staff account that can manage products.
• Marketplace sellers fill in features on their own products, which then show in comparisons.

When the module is off, Compare buttons and the compare bar disappear, and the compare page shows a "not available" message. Shoppers' lists are kept and come back if you switch it on again.