add login router

frontend/src/routes/login/login.tsx

@@ -0,0 +1,3 @@
+export default function LoginView() {
+  return <p>login</p>;
+}

frontend/src/routes/router.tsx

@@ -1,4 +1,5 @@
 import { Routes, Route } from 'react-router-dom';
+import LoginView from './login/login';
 import ProcessingView from './processing/processing';
 import UploadView from './upload/upload';
 import ViewView from './view/view';
@@ -7,6 +8,7 @@ export default function AppRouter() {
   return (
     <Routes>
       <Route path="/" element={<UploadView />} />
+      <Route path="login" element={<LoginView />} />
       <Route path="processing" element={<ProcessingView />} />
       <Route path="view/:hash" element={<ViewView />} />
     </Routes>