feat(前端): 新增 WIP 分布矩阵透视表页面

- MatrixBoard.tsx: Radio切换 按人员/按工序，动态交叉表转换(规格型号为行)
- 单元格显示设备数量+主负责人，首列规格固定左、末列合计固定右，bordered Excel风格
- 路由 /admin/matrix 注册，侧边栏新增「WIP 分布矩阵」入口

frontend/src/services/dashboardApi.ts

@@ -71,6 +71,13 @@ export interface OperationDetail {
   time: string;
 }
 
+export interface WipMatrixRow {
+  spec_model: string;
+  dimension_key: string;
+  count: number;
+  assignees: string[];
+}
+
 export interface PersonDevice {
   product_id: string;
   serial_number: string;
@@ -177,6 +184,11 @@ export async function fetchOperationDetail(
   return data;
 }
 
+export async function fetchWipMatrix(dimension: "assignee" | "task_name"): Promise<WipMatrixRow[]> {
+  const { data } = await api.get<WipMatrixRow[]>("/dashboard/wip-matrix", { params: { dimension } });
+  return data;
+}
+
 export async function fetchPeopleWorkload(): Promise<PersonWorkload[]> {
   const { data } = await api.get<PersonWorkload[]>("/dashboard/people-workload");
   return data;