feat: 图片创作每张图加「加入模特库」按钮 (row41)

图片工作台单图「更多」气泡新增「加入模特库」(与「加入资产库」并列):
把该生成图复用为模特形象图建 Model 条目,加入后变「已加入模特库」禁用。

后端新增 POST /api/models/enroll-asset/(ModelLibraryViewSet.enroll_asset):
复用已有资产作 portrait_asset 建 Model,不重新上传/不二次扣费;同一资产幂等返回。
需部署生效(后端)。

构建: tsc --noEmit=0, npm run build=0; 后端 py_compile OK。

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

core/backend/apps/assets/views.py

@@ -399,6 +399,29 @@ class ModelLibraryViewSet(ModelViewSet):
             )
         return Response(ModelLibrarySerializer(model).data, status=status.HTTP_201_CREATED)
 
+    @action(detail=False, methods=["post"], url_path="enroll-asset")
+    def enroll_asset(self, request):
+        """图片创作「加入模特库」:把一张已生成的图复用为模特形象图建 Model 条目。
+        资产生成时已落库扣过费,此处只引用、不重新上传/不二次扣费。同一资产已建过则幂等返回。"""
+        team = self.get_team()
+        asset_id = request.data.get("asset_id")
+        asset = Asset.objects.filter(id=asset_id, team=team, is_deleted=False).first() if asset_id else None
+        if asset is None:
+            raise ValidationError({"asset_id": "资产不存在或不属于本团队"})
+        existing = Model.objects.filter(team=team, portrait_asset=asset, is_deleted=False).first()
+        if existing is not None:
+            return Response(ModelLibrarySerializer(existing).data, status=status.HTTP_200_OK)
+        name = (request.data.get("name") or (asset.name or "模特").split("·")[0].strip() or "模特")[:255]
+        model = Model.objects.create(
+            team=team,
+            created_by=request.user,
+            name=name,
+            source=Model.Source.AI,
+            portrait_asset=asset,
+            metadata={"source": "enroll_from_asset", "asset_id": str(asset.id)},
+        )
+        return Response(ModelLibrarySerializer(model).data, status=status.HTTP_201_CREATED)
+
 
 class AssetUploadView(APIView):
     parser_classes = [MultiPartParser, FormParser]