feat(zone): 三区标记M3后端——KPI values/bot-kpis响应补calculated_at时间字段(updated_at/value_updated_at/source_batch)，供BotSourceTag展示 (three-zone P0-①)

backend/app/api/kpis.py

@@ -548,6 +548,8 @@ def list_kpi_values(
             "source_batch": v.source_batch or "",
             "data_status": v.data_status,
             "remark": v.remark or "",
+            # P0-① 三区标注: C区Bot回填时间
+            "updated_at": v.calculated_at.strftime("%Y-%m-%d %H:%M") if v.calculated_at else None,
         } for v in vals]
     }
 
@@ -608,6 +610,8 @@ def get_kpi(kpi_id: int, db: Session = Depends(get_db), entity_id: int = Depends
             "source_type": v.source_type,
             "data_status": v.data_status,
             "source_batch": v.source_batch,
+            # P0-① 三区标注: C区Bot回填时间（UI BotSourceTag 消费）
+            "updated_at": v.calculated_at.strftime("%Y-%m-%d %H:%M") if v.calculated_at else None,
         })
     return result