feat: 宏观状态动态从主干任务获取+任务树assignee中文姓名映射(后端+前端)

backend/app/schemas/product.py

@@ -78,6 +78,7 @@ class ProductScanResponse(BaseModel):
     created_at: datetime
     top_level_tasks: list[TaskSummaryResponse] = []
     task_tree: list[TaskResponse] = []
+    assignee_names: dict[str, str] = {}  # 🔧 username→中文姓名映射
 
     model_config = {"from_attributes": True}