feat(ux): implement sprint 11 user experience module

docs/backend-platform/business-apis.md

@@ -130,6 +130,49 @@ Purpose:
 Must not change:
 - acknowledgement contract expected by frontend engagement form.
 
+## /me/wishlist (future-ready)
+Purpose:
+- authenticated wishlist synchronization across devices.
+
+High-level response shape:
+- wishlist product references
+- optional addedAt metadata
+
+Tenant rule:
+- wishlist entries must remain tenant-scoped.
+
+## /me/compare (future-ready)
+Purpose:
+- optional compare list synchronization for authenticated users.
+
+High-level response shape:
+- compared product references
+- optional addedAt metadata
+
+Tenant rule:
+- compare list must be isolated by tenant + user.
+
+## /me/saved-searches (future-ready)
+Purpose:
+- persist and restore saved search presets.
+
+High-level response shape:
+- saved query/filter/sort presets
+- timestamps and id
+
+Tenant rule:
+- saved searches must be tenant-scoped and user-scoped.
+
+## /me/recently-viewed (future-ready)
+Purpose:
+- synchronize recently viewed product history for authenticated users.
+
+High-level response shape:
+- product references + viewedAt metadata
+
+Tenant rule:
+- history must remain tenant-scoped and privacy-safe.
+
 ## /categories
 Purpose:
 - category tree retrieval