feat(client): 首次登录改密守卫与错误文案(F35,F38)

- 登录响应支持 mustChangePassword 并强制跳转改密页
- 新增改密页面与全局路由守卫
- 完善 AUTH_002/SYS_429/VALID_00x 等错误提示

client/src/router/index.tsx

@@ -2,6 +2,7 @@ import { Navigate, Route, Routes } from "react-router-dom";
 import { AppShellLayout } from "../layouts/AppShellLayout";
 import { AuthLayout } from "../layouts/AuthLayout";
 import { AuditLogsPage } from "../pages/AuditLogsPage";
+import { ChangePasswordPage } from "../pages/ChangePasswordPage";
 import { DashboardPage } from "../pages/DashboardPage";
 import { DelegationsPage } from "../pages/DelegationsPage";
 import { ForbiddenPage } from "../pages/ForbiddenPage";
@@ -31,6 +32,17 @@ export function AppRouter() {
         <Route index element={<LoginPage />} />
       </Route>
 
+      <Route
+        path="/change-password"
+        element={
+          <RequireAuth>
+            <AuthLayout />
+          </RequireAuth>
+        }
+      >
+        <Route index element={<ChangePasswordPage />} />
+      </Route>
+
       <Route
         path="/"
         element={