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/components/layout/AdminLayout.tsx

@@ -1,5 +1,5 @@
 import { NavLink, Outlet, useLocation, useNavigate, Navigate } from "react-router-dom";
-import { QrCode, Package, ArrowLeft, LayoutDashboard, Smartphone, GitBranch, LogOut, User, Users, BarChart3 } from "lucide-react";
+import { QrCode, Package, ArrowLeft, LayoutDashboard, Smartphone, GitBranch, LogOut, User, Users, BarChart3, Table2 } from "lucide-react";
 import { useAuth } from "../../contexts/AuthContext";
 
 const MENU = [
@@ -33,6 +33,12 @@ const MENU = [
     icon: BarChart3,
     description: "人员效能 / 设备流转 ECharts 可视化",
   },
+  {
+    title: "WIP 分布矩阵",
+    path: "/admin/matrix",
+    icon: Table2,
+    description: "规格型号 × 人员/工序 在制品透视表",
+  },
 ];
 
 export default function AdminLayout() {