F-090 — Implementer evidence

Changes

project/src/modules/catalog/api/catalog.routes.ts
- serializeProduct now includes brand and expirationDate, which are already present on the domain/repository product.
- This fixes /catalog/products responses consumed by the admin listing.
project/apps/admin/src/features/products/components/sections/InventorySection.tsx
- SKU and EAN display/edit controls now use rows[variant.id].variant, the state updated after a successful PATCH, instead of the immutable initial variants array.
- This keeps the newly saved value visible after leaving edit mode and when opening the editor again.

Root npm run typecheck → exit 0
Admin npx tsc --noEmit → exit 0
Admin ESLint on InventorySection.tsx → exit 0
Backend PATCH route remains /products/:id/variants/:variantId; no API contract or schema change.