feat: add login gate and admin navigation to App.vue

src/App.vue

@@ -1,20 +1,48 @@
 <script setup lang="ts">
-import { ref } from 'vue'
+import { onMounted, ref } from 'vue'
+import AdminPage from './components/AdminPage.vue'
 import BookListPage from './components/BookListPage.vue'
+import LoginPage from './components/LoginPage.vue'
 import WorkspaceView from './components/WorkspaceView.vue'
+import { useAuth } from './composables/useAuth'
 
+const { isLoggedIn, fetchMe } = useAuth()
 const currentBookId = ref<string | null>(null)
+const showAdmin = ref(false)
+
+onMounted(async () => {
+  await fetchMe()
+})
 
 function openBook(id: string): void {
   currentBookId.value = id
+  showAdmin.value = false
 }
 
 function backToList(): void {
   currentBookId.value = null
 }
+
+function openAdmin(): void {
+  showAdmin.value = true
+  currentBookId.value = null
+}
+
+function closeAdmin(): void {
+  showAdmin.value = false
+}
 </script>
 
 <template>
-  <BookListPage v-if="!currentBookId" @open="openBook" />
-  <WorkspaceView v-else :key="currentBookId" :book-id="currentBookId" @back="backToList" />
+  <LoginPage v-if="!isLoggedIn" @success="fetchMe" />
+  <template v-else>
+    <AdminPage v-if="showAdmin" @back="closeAdmin" />
+    <WorkspaceView
+      v-else-if="currentBookId"
+      :key="currentBookId"
+      :book-id="currentBookId"
+      @back="backToList"
+    />
+    <BookListPage v-else @open="openBook" @admin="openAdmin" />
+  </template>
 </template>