feat(images): 期2 图片趴三类 — 模特上身图/平台套图/自由创作 归类+成组+接模特库

后端:
- 独立生图三类归类:model+product→model_tryon(模特上身图,引用模特库,不送审) / cover→platform_kit(平台套图) / image→free_create(自由创作);生成演员(model 无 product)仍→person(视频角色,留期3)
- 成组:每次提交一个 batch_id 串起整批,落 asset.metadata;另记 mode + model_entity_id(上身图溯源模特库)
- generate-image 端点透传 model_entity_id;资产库 _tab_q+summary 加 tryon/kits/creations 三类桶
- 单测 StandaloneCategoryTests 直跑 worker 验四态归类全绿(绕开异步 .delay)

前端:
- 资产库 library.tsx 加三类 tab(模特上身图/平台套图/自由创作)+ 计数 + 筛选维度
- ai-tools 模特选择器数据源 person→模特库(listModels 映射,选中传形象图当参考 = 引用模特库),ActorLibrary 同源
- api.ts submitGenerateImage 加 model_entity_id

验收:tsc+build 全绿;无头 0 console error(资产库三类 tab 各归类正确、模特选择器 5 张取自模特库)
基线既有 3 失败(StandaloneImageReferenceTests 异步漂移)零新增

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/backend/apps/ai/views.py

@@ -32,10 +32,11 @@ class GenerateImageView(APIView):
         product_id = str(request.data.get("product_id") or "").strip() or None
         reference_product = bool(request.data.get("reference_product"))
         model_id = str(request.data.get("model_id") or "").strip() or None
+        model_entity_id = str(request.data.get("model_entity_id") or "").strip() or None
         ratio = str(request.data.get("ratio") or "").strip() or None
         team = get_current_team(request.user)
         try:
-            tasks = enqueue_standalone_images(team=team, user=request.user, prompt=prompt, mode=mode, count=count, product_id=product_id, reference_product=reference_product, model_id=model_id, ratio=ratio)
+            tasks = enqueue_standalone_images(team=team, user=request.user, prompt=prompt, mode=mode, count=count, product_id=product_id, reference_product=reference_product, model_id=model_id, model_entity_id=model_entity_id, ratio=ratio)
         except ValueError as exc:  # 无可用模型 / 余额不足等,立即反馈
             return Response({"detail": str(exc)}, status=status.HTTP_400_BAD_REQUEST)
         return Response(