- New is_pinterest boolean on ShopProductListingModel, settable via the
existing create/update product endpoints (multipart form field)
- /shop-products/discover accepts ?pinterest=true to show only
Pinterest-tagged products across shops; skips the tagged-posts merge
under this filter since those posts aren't Pinterest-tagged themselves
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>