Products: carry the IMVU parent's image and categories

Revisions with an IMVU parent store its public info (image, category path, gender)
from IMVU's product API, looked up after registering and in a periodic pass.
Product views gain parent, image and categories; GET /products takes category and
limit. The website shows the image on cards and product pages.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/api.md

@@ -49,6 +49,13 @@ is. Codes: `invalid`, `signed_out`, `forbidden`, `not_found`, `no_such_imvu_acco
 | `DELETE /api/v1/account/links/:imvu` | unlink |
 | `POST /api/v1/account/signout-computers` | signs T5DE out on all their computers |
 
+## Products, catalogs and libraries
+
+The routes and tokens are in docs/products.md. Products are `{id, name, description, rating, latest, creator,
+creatorUsername, parent, image, categories, createdAt, updatedAt}`; `parent`, `image` and `categories` come from the
+latest revision (its IMVU parent's public info). `GET /api/v1/products` takes `q`, `creator`, `category` (an IMVU
+category ID) and `limit` (1-200, default 60).
+
 ## Age verification
 
 Vendor-neutral (docs/design.md, "Age"): IMVU's answer is recorded when an account is linked or checked again;