Create a vendor product by selecting from the master catalog. The product name, weight, dimensions, category, brand, ingredients, allergens, and skin types are automatically copied from the master product. Vendor must provide pricing and SKU. Images are referenced from the master product unless custom images are uploaded.

The product name is NOT overridable to maintain consistency across vendors. Description and usage instructions can optionally be overridden.

If the vendor already has a product linked to the same master product, a warning is included in the response but creation is still allowed (supports different SKUs/variants).