fix(adminfront): fix ReferenceErrors and null checks in UI components

- Import and initialize 'navigate' in TenantUsersPage and TenantAdminsAndOwnersTab.
- Use optional chaining for 'user.id' in UserDetailPage to prevent runtime errors during initial load.

adminfront/src/features/tenants/routes/TenantAdminsAndOwnersTab.tsx

@@ -11,7 +11,7 @@ import {
 } from "lucide-react";
 import { useState } from "react";
 import { useAuth } from "react-oidc-context";
-import { useParams } from "react-router-dom";
+import { useNavigate, useParams } from "react-router-dom";
 import { Badge } from "../../../components/ui/badge";
 import { Button } from "../../../components/ui/button";
 import {
@@ -66,6 +66,7 @@ function mergePendingMembers(
 
 export function TenantAdminsAndOwnersTab() {
   const auth = useAuth();
+  const navigate = useNavigate();
   const currentUserId = auth.user?.profile.sub;
   const { tenantId } = useParams<{ tenantId: string }>();
   const queryClient = useQueryClient();

adminfront/src/features/tenants/routes/TenantUsersPage.tsx

@@ -9,7 +9,7 @@ import {
   UserMinus,
   UserPlus,
 } from "lucide-react";
-import { Link, useParams } from "react-router-dom";
+import { Link, useNavigate, useParams } from "react-router-dom";
 import { Badge } from "../../../components/ui/badge";
 import { Button } from "../../../components/ui/button";
 import {
@@ -38,6 +38,7 @@ import { t } from "../../../lib/i18n";
 
 function TenantUsersPage() {
   const params = useParams<{ tenantId: string }>();
+  const navigate = useNavigate();
   const tenantId = params.tenantId ?? "";
   const queryClient = useQueryClient();
 

adminfront/src/features/users/UserDetailPage.tsx

@@ -1078,7 +1078,7 @@ function UserDetailPage() {
                         id="role"
                         className="flex h-11 w-full rounded-md border border-input bg-background px-3 py-2 text-sm shadow-sm transition-colors focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-primary disabled:opacity-50"
                         {...register("role")}
-                        disabled={profile?.role !== "super_admin" || profile?.id === user.id}
+                        disabled={profile?.role !== "super_admin" || profile?.id === user?.id}
                       >
                         <option value="super_admin">
                           {t("ui.admin.role.super_admin", "시스템 관리자")}