feat(全局概览): 快捷入口下方新增人员操作统计区域

- 表格展示每人 接收/转交/上传备注/总次数，按总次数降序
- 跟随顶部时间筛选(今天/近7天/近30天/自定义)联动刷新

frontend/src/services/dashboardApi.ts

@@ -54,6 +54,15 @@ export interface RejectedTask {
   rejected_at: string | null;
 }
 
+export interface UserOperation {
+  user_id: string;
+  user_name: string;
+  receive_count: number;
+  transfer_count: number;
+  record_count: number;
+  total: number;
+}
+
 export interface PersonDevice {
   product_id: string;
   serial_number: string;
@@ -142,6 +151,14 @@ export async function fetchRejectedTasks(since?: string, until?: string): Promis
   return data;
 }
 
+export async function fetchUserOperations(since?: string, until?: string): Promise<UserOperation[]> {
+  const params: Record<string, string> = {};
+  if (since) params.since = since;
+  if (until) params.until = until;
+  const { data } = await api.get<UserOperation[]>("/dashboard/user-operations", { params });
+  return data;
+}
+
 export async function fetchPeopleWorkload(): Promise<PersonWorkload[]> {
   const { data } = await api.get<PersonWorkload[]>("/dashboard/people-workload");
   return data;