feat(backend): 新增 /dashboard/user-operations/detail 操作明细下钻接口

- 按人+操作类型(receive/transfer/record)查询明细：任务/产品/备注/时间
- record 明细与该人统计口径一致(名下任务手动备注，排除系统自动)

backend/app/api/v1/endpoints/dashboard.py

@@ -11,6 +11,7 @@ from app.services.dashboard_service import (
     get_completed_tasks, CompletedTask,
     get_rejected_tasks, RejectedTask,
     get_user_operations, UserOperation,
+    get_user_operation_detail, OperationDetail,
     get_people_workload, PersonWorkload,
     get_people_history, PersonHistoryRecord,
     search_product_messages, ProductMessageList,
@@ -83,6 +84,22 @@ async def user_operations(
     return await get_user_operations(db, since=since_dt, until=until_dt)
 
 
+@router.get("/user-operations/detail", response_model=list[OperationDetail])
+async def user_operations_detail(
+    user_id: str = Query(..., description="人员ID(username)"),
+    action_type: str = Query(..., description="操作类型: receive/transfer/record"),
+    since: str | None = Query(None, description="起始日期 ISO"),
+    until: str | None = Query(None, description="截止日期 ISO"),
+    db: AsyncSession = Depends(get_db),
+):
+    """人员操作明细下钻 — 某人在指定时段的接收/转交/上传备注明细"""
+    since_dt = datetime.fromisoformat(since) if since else None
+    until_dt = datetime.fromisoformat(until) if until else None
+    return await get_user_operation_detail(
+        db, user_id, action_type, since=since_dt, until=until_dt,
+    )
+
+
 @router.get("/people-workload", response_model=list[PersonWorkload])
 async def people_workload(
     db: AsyncSession = Depends(get_db),