fix: align favorites page with post adapter

docs/backend-wallet-favorites-production-fixes.md

@@ -187,7 +187,13 @@ If backend decides to keep the simplified `{ address }` login, please explicitly
 
 ## Priority 2 — Normalize favorites response contract
 
-Frontend currently supports the staging response shape, but the response should be made explicit.
+Frontend currently supports the staging response shape, but the response must be made explicit and self-sufficient. The frontend renders favorites as plain strings and does not perform per-resource translation, slug-to-name lookup, category fetching, or localization fallback.
+
+### `lang` semantics
+
+`?lang=<ui-lang>` on `GET /api/favorites` is a **display resolution hint**, not a filter. It must NOT filter favorites by post language. A user who favorited Chinese and English posts must see both regardless of `lang`. `lang` only tells the backend which language to resolve display strings into.
+
+**Current staging behavior is wrong**: sending `?lang=en` on staging returns zero items for users whose favorites are Chinese posts, and vice versa. Because of this, the frontend currently does NOT send `lang` on `GET /api/favorites`. Once the backend treats `lang` as a resolve hint instead of a filter, the frontend will send `lang` again so resolved strings come back in the user's UI language.
 
 ### Favorites list
 
@@ -196,36 +202,50 @@ GET /api/favorites?lang=&limit=&page=&sort=&category=&q=
 Authorization: Bearer <token>
 ```
 
-Current staging response observed:
+Required production response:
 
 ```json
 {
   "items": [
     {
       "id": "...",
-      "postType": "image",
+      "title": "...",
+      "description": "...",
+      "type": "...",
       "categoryId": 11,
       "categorySlug": "official-assets",
-      "language": "zh",
-      "title": "..."
+      "categoryName": "...",
+      "language": "...",
+      "sourceLanguage": "...",
+      "coverImage": "...",
+      "updatedAt": "...",
+      "publishedAt": "...",
+      "favoriteCount": 0,
+      "availability": "available"
     }
-  ]
-}
-```
-
-Recommended production response:
-
-```json
-{
-  "items": [],
+  ],
   "page": 1,
   "limit": 24,
   "total": 0
 }
 ```
 
+Fields that must be present and pre-resolved by the backend when `lang` is supplied:
+
+- `title` — already in `lang`. If a translation does not exist, fall back to the post's source language.
+- `description` — same rule as `title`.
+- `categoryName` — localized category name for `lang`. Frontend must not look up categories by slug.
+- `type` — a string the frontend can display directly. If you need both a raw type code and a label, add `typeLabel` and use that for display.
+- `language` — a human-readable label for the post's source language, in `lang`. e.g. for `lang=zh-CN` a Chinese post returns `language: "中文"`. If you prefer to keep `language` as a code, add `languageLabel` and use it for display.
+- `coverImage` — a usable image URL. The frontend will not fall back to attachment arrays.
+- `updatedAt`, `publishedAt` — ISO timestamps.
+- `favoriteCount` — optional but recommended.
+- `availability` — `"available" | "unavailable"`.
+
 `page`, `limit`, and `total` are needed for correct pagination.
 
+The frontend must never need to: load `/api/categories`, parse `localizations` maps, walk `attachments`, or translate `type` / `language` codes for this page.
+
 ### Favorite status by ids
 
 ```http