fix(10-13): admin sidebar bleed and keyboard instance resolution

- App.vue: add v-else-if branch for admin routes that renders only router-view (no AppSidebar)
- App.vue: replace routeViewRef with getFileManagerInstance() using matched.find(r => r.instances?.default)
- App.vue: remove unused ref import (Gap 3 + Gap 4)

frontend/src/App.vue

@@ -1,9 +1,10 @@
 <template>
   <AuthLayout v-if="route.meta.layout === 'auth'" />
+  <router-view v-else-if="route.matched.some(r => r.meta.requiresAdmin)" />
   <div v-else class="flex h-screen overflow-hidden">
     <AppSidebar />
     <main class="flex-1 overflow-y-auto">
-      <router-view ref="routeViewRef" />
+      <router-view />
     </main>
   </div>
   <ToastContainer />
@@ -11,8 +12,8 @@
 </template>
 
 <script setup>
-import { ref, onMounted, onUnmounted } from 'vue'
-import { useRoute } from 'vue-router'
+import { onMounted, onUnmounted } from 'vue'
+import { useRoute, useRouter } from 'vue-router'
 import AppSidebar from './components/layout/AppSidebar.vue'
 import AuthLayout from './layouts/AuthLayout.vue'
 import ToastContainer from './components/ui/ToastContainer.vue'
@@ -20,11 +21,15 @@ import OsDragOverlay from './components/layout/OsDragOverlay.vue'
 import { useTopicsStore } from './stores/topics.js'
 
 const route = useRoute()
+const router = useRouter()
 const topicsStore = useTopicsStore()
-const routeViewRef = ref(null)
+
+function getFileManagerInstance() {
+  return router.currentRoute.value.matched.find(r => r.instances?.default)?.instances?.default ?? null
+}
 
 function onOsFilesDropped(files) {
-  routeViewRef.value?.handleOsDrop?.(files)
+  getFileManagerInstance()?.handleOsDrop?.(files)
 }
 
 function onKeydown(e) {
@@ -34,16 +39,16 @@ function onKeydown(e) {
 
   if (e.key === '/' && !e.ctrlKey && !e.metaKey) {
     e.preventDefault()
-    routeViewRef.value?.focusSearch?.()
+    getFileManagerInstance()?.focusSearch?.()
   }
   if (e.key === 'Escape') {
-    routeViewRef.value?.clearSearch?.()
+    getFileManagerInstance()?.clearSearch?.()
   }
   if (e.key === 'u' || e.key === 'U') {
-    routeViewRef.value?.triggerUpload?.()
+    getFileManagerInstance()?.triggerUpload?.()
   }
   if (e.key === 'n' || e.key === 'N') {
-    routeViewRef.value?.startNewFolder?.()
+    getFileManagerInstance()?.startNewFolder?.()
   }
 }